10 Easy Arithmetic Tricks

Math can be terrifying for many people. This list will hopefully improve your general knowledge of mathematical tricks and your speed when you need to do math in your head.

1. The 11 Times Trick

We all know the trick when multiplying by ten – add 0 to the end of the number, but did you know there is an equally easy trick for multiplying a two digit number by 11? This is it:

Take the original number and imagine a space between the two digits (in this example we will use 52:

5_2

Now add the two numbers together and put them in the middle:

5_(5+2)_2

That is it – you have the answer: 572.

If the numbers in the middle add up to a 2 digit number, just insert the second number and add 1 to the first:

9_(9+9)_9

(9+1)_8_9

10_8_9

1089 – It works every time.

2. Quick Square

If you need to square a 2 digit number ending in 5, you can do so very easily with this trick. Mulitply the first digit by itself + 1, and put 25 on the end. That is all!

252 = (2x(2+1)) & 25
2 x 3 = 6
625


3. Multiply by 5

Most people memorize the 5 times tables very easily, but when you get in to larger numbers it gets more complex – or does it? This trick is super easy.

Take any number, then divide it by 2 (in other words, halve the number). If the result is whole, add a 0 at the end. If it is not, ignore the remainder and add a 5 at the end. It works everytime:

2682 x 5 = (2682 / 2) & 5 or 0
2682 / 2 = 1341 (whole number so add 0)
13410

Let’s try another:
5887 x 5
2943.5 (fractional number (ignore remainder, add 5)
29435

4. Multiply by 9

This one is simple – to multiple any number between 1 and 9 by 9 hold both hands in front of your face – drop the finger that corresponds to the number you are multiplying (for example 9×3 – drop your third finger) – count the fingers before the dropped finger (in the case of 9×3 it is 2) then count the numbers after (in this case 7) – the answer is 27.





5. Multiply by 4

This is a very simple trick which may appear obvious to some, but to others it is not. The trick is to simply multiply by two, then multiply by two again:

58 x 4 = (58 x 2) + (58 x 2) = (116) + (116) = 232


6. Calculate a Tip

If you need to leave a 15% tip, here is the easy way to do it. Work out 10% (divide the number by 10) – then add that number to half its value and you have your answer:

15% of $25 = (10% of 25) + ((10% of 25) / 2)
$2.50 + $1.25 = $3.75


7. Tough Multiplication

If you have a large number to multiply and one of the numbers is even, you can easily subdivide to get to the answer:

32 x 125, is the same as:
16 x 250 is the same as:
8 x 500 is the same as:
4 x 1000 = 4,000

8. Dividing by 5

Dividing a large number by five is actually very simple. All you do is multiply by 2 and move the decimal point:

195 / 5

Step1: 195 * 2 = 390
Step2: Move the decimal: 39.0 or just 39

2978 / 5

step 1: 2978 * 2 = 5956
Step2: 595.6







9. Subtracting from 1,000
To subtract a large number from 1,000 you can use this basic rule: subtract all but the last number from 9, then subtract the last number from 10:

1000
-648

step1: subtract 6 from 9 = 3
step2: subtract 4 from 9 = 5
step3: subtract 8 from 10 = 2

answer: 352


10. Assorted Multiplication Rules
Multiply by 5: Multiply by 10 and divide by 2.
Multiply by 6: Sometimes multiplying by 3 and then 2 is easy.
Multiply by 9: Multiply by 10 and subtract the original number.
Multiply by 12: Multiply by 10 and add twice the original number.
Multiply by 13: Multiply by 3 and add 10 times original number.
Multiply by 14: Multiply by 7 and then multiply by 2
Multiply by 15: Multiply by 10 and add 5 times the original number, as above.
Multiply by 16: You can double four times, if you want to. Or you can multiply by 8 and then by 2.
Multiply by 17: Multiply by 7 and add 10 times original number.
Multiply by 18: Multiply by 20 and subtract twice the original number (which is obvious from the first step).
Multiply by 19: Multiply by 20 and subtract the original number.
Multiply by 24: Multiply by 8 and then multiply by 3.
Multiply by 27: Multiply by 30 and subtract 3 times the original number (which is obvious from the first step).
Multiply by 45: Multiply by 50 and subtract 5 times the original number (which is obvious from the first step).
Multiply by 90: Multiply by 9 (as above) and put a zero on the right.
Multiply by 98: Multiply by 100 and subtract twice the original number.
Multiply by 99: Multiply by 100 and subtract the original number.

Bonus: Percentages

Yanni in comment 23 gave an excellent tip for working out percentages, so I have taken the liberty of duplicating it here:

Find 7 % of 300. Sound Difficult?

Percents: First of all you need to understand the word “Percent.” The first part is PER , as in 10 tricks per listverse page. PER = FOR EACH. The second part of the word is CENT, as in 100. Like Century = 100 years. 100 CENTS in 1 dollar… etc. Ok… so PERCENT = For Each 100.

So, it follows that 7 PERCENT of 100, is 7. (7 for each hundred, of only 1 hundred).
8 % of 100 = 8. 35.73% of 100 = 35.73
But how is that useful??

Back to the 7% of 300 question. 7% of the first hundred is 7. 7% of 2nd hundred is also 7, and yep, 7% of the 3rd hundred is also 7. So 7+7+7 = 21.

If 8 % of 100 is 8, it follows that 8% of 50 is half of 8 , or 4.

Break down every number that’s asked into questions of 100, if the number is less then 100, then move the decimal point accordingly.

EXAMPLES:
8%200 = ? 8 + 8 = 16.
8%250 = ? 8 + 8 + 4 = 20.
8%25 = 2.0 (Moving the decimal back).
15%300 = 15+15+15 =45.
15%350 = 15+15+15+7.5 = 52.5

Also it’s usefull to know that you can always flip percents, like 3% of 100 is the same as 100% of 3.

35% of 8 is the same as 8% of 35.

Maths Myth

Tonight I'm looking for people perception about maths or mathematics. Here an article saying about what people think about maths. I quite agree with the writer because it really happen in our daily life. People sometimes feel maths is difficult and only maths student can really solve the problem about maths. For the simple case like counting the total payment of the things we buy, i do not shame to say that "sorry, I'm not good in maths. Can you just calculate for me?" That attitude do not show the real reason we cannot calculate. The real reason is we lazy to think. Instead of saying "I'm not good in maths, why not we just say "I'm not good in reading". What will we feel when we say "I'm not good in reading"? It really shame right? That the society perception about maths.

You Can Do Math!

We've probably all been at a restaurant with a group of people who want to pay individually, but only one bill arrives. You then find yourself in the position of trying to determine how much each person owes. What happens? You look over the bill with a slight wave of panic at having to figure out your total, but instead you say, "I'm no good at math" and you proceed to pass it to the next person who immediately responds the same way you did. Eventually and usually with some hesitancy, one person takes ownership over the bill and calculates the individual costs or divides the total by the number of people at the table. Did you notice how quickly people say that they were no good at math? Did anyone say, I'm no good at reading? or I can't read? When and why is it acceptable in our society to say we're no good at math? We'd be embarassed to declare that we're no good at reading yet it's quite acceptable in our society to say that we can't do math! In today's information age, mathematics is needed more than it ever was before - we need math! Problem solving skills are highly prized by employers today. There is an increasing need for math and the first step needed is a change in our attitudes and beliefs about math.

Attitudes and Misconceptions

Do your experiences in math cause you anxiety? Have you been left with the impression that math is difficult and only some people are 'good' at math? Are you one of those people who believe that you 'can't do math', that you're missing that 'math gene'? Do you have the dreaded disease called Math Anxiety? Read on, sometimes our school experiences leave us with the wrong impression about math. There are many misconceptions that lead one to believe that only some individuals can do math. It's time to dispel those common myths. Everyone can be successful in math when presented with opportunities to succeed, an open mind and a belief that one can do math.

True or False: There is one way to solve a problem.

False: There are a variety of ways to solve math problems and a variety of tools to assist with the process. Think of the process you use when you try to determine how many pieces of pizza will 5 people will get with 2 and a half 6 slice pizzas. Some of you will visualize the pizzas, some will add the total number of slizes and divide by 5. Does anyone actually write the algorithm? Not likely! There are a variety of ways to arrive at the solution, and everyone uses their own learning style when solving the problem.

True or False: You need a 'math gene' or dominance of your left brain to be successful at math.

False: Like reading, the majority of people are born with the ability to do math. Children and adults need to maintain a positive attitude and the belief that they can do math. Math must be nurtured with a supportive learning environment that promotes risk taking and creativity, one that focuses on problem solving.

True or False: Children don't learn the basics anymore because of a reliance on calculators and computers.

False: Research at this time indicates that calculators do not have a negative impact on achievement. The calculator is a powerful teaching tool when used appropriately. Most teachers focus on the effective use of a calculator. Students are still required to know what they need to key into the calculator to solve the problem.

True or False: You need to memorize a lot of facts, rules and formulas to be good at math.

False False! As stated earlier, there's more than one way to solve a problem. Memorizing procedures is not as effective as conceptually understanding concepts. For instance, memorizing the fact 9x9 is not as important as understanding that 9x9 is 9 groups of 9. Applying thinking skills and creative thought lead to a better understanding of math. Signs of understanding include those "Aha" moments! The most important aspect to learning math is understanding. Ask yourself after solving a math problem: are you applying a series of memorized steps/procedures, or do you really 'understand' how and why the procedure works.

Answer the questions: How do you know it's right? Is there more than one way to solve this problem? When questions like this are answered, you're on your way to becoming a better math problem solver.

True or False: Keep giving more drill and repetition questions until children get it!

False False, find another way to teach or explain the concept. All too often, children receive worksheets with drill and repetition, this only leads to overkill and negative math attitudes! When a concept isn't understood, it's time to find another method of teaching it. No new learning has ever occurred as a result of repetition and drill. Negative attitudes toward math are usually the result of overuse of worksheets.

In summary:

Positive attitudes towards math are the first step to success. When does the most powerful learning usually occur? When one makes a mistake! If you take the time to analyze where you go wrong, you can't help but learn. Never feel badly about making mistakes in mathematics.

Societal needs have changed, thus math has changed. We are now in an information age with technology paving the way. It is no longer enough to do computations; that's what calculators and computers are for. Math today requires decisions about which keys to punch in and which graph to use, not how to construct them! Math requires creative problem solving techniques. Today's math requires real-life problems to solve, a skill highly prized by employers today. Math requires knowing when and how to use the tools to assist in the problem solving process. This happens as early as pre-kindergarten when children seek counters, an abacus, blocks and a variety of other manipulatives. Family involvement is also critical in nurting a positive and risk-taking attitudes in math. The sooner this begins, the sooner one will become more successful in math.

Math has never been more important, technology demands that we work smarter and have stronger problem solving skills. Experts suggest that in the next 5-7 years there will be twice as much math as there is today. There are many reasons to learn math and it's never too late to start!

Another terrific strategy is to Learn From Your Mistakes Sometimes the most powerful learning stems from the mistakes you make.

Credited : maths.about.com

What do Mathematician do?

When i first taking my degree in Mathematial Science, many people ask me "what will you do after you finish your degree?" or "will you be a teacher after you graduated?". Questions like that are very familiar among us, as mathematical science students. People outside this area do not know what are mathematician do. Some of us also do not know what are our specific job. For a long time we wonder that matter.

When I search in internet, i found a website about mathematician. AMS or American Mathematical Societies is a society for mathematician in US.

Mission of AMS

The AMS, founded in 1888 to further the interests of mathematical research and scholarship, serves the national and international community through its publications, meetings, advocacy and other programs, which

•  promote mathematical research, its communication and uses,

•  encourage and promote the transmission of mathematical understanding and skills,

•  support mathematical education at all levels,

•  advance the status of the profession of mathematics, encouraging and facilitating full participation of all individuals,

•   foster an awareness and appreciation of mathematics and its connections to other disciplines and everyday life

From this website, i found a journal that will answered all questions and remove our doubt about mathematician.According to that article, when you are asked "What do mathematicians do?", you can say: I like to think we are just like lawyers or philosophers who explore the meanings of our everyday concepts, we are like inventors who employ analogies to solve problems, and we are like marketers who try to convince others they ought to think “Kodak” when they hear “photography” (or the competition, who try to convince them that they ought to think “Fuji”). Moreover, some of the time, our work is not unlike solving a two-thousand-piece jigsaw puzzle, all in one color. That surely involves lots of scut work, but also ingenuity along the way in dividing up the work, sorting the pieces, and knowing that it often makes sense to build the border first.

UPSI rally

PETALING JAYA:  Student activists saw an ominous start to the new year when about 100 of them were violently dispersed by the police for staging a peaceful assembly in front of the Universiti Perguruan Sultan Idris (UPSI) in Tanjung Malim early this morning.

The students had started gathering since 12.30am to demand for academic freedom and to protest against the Universities and University Colleges Act. They had also wanted the UPSI to drop charges against student leader Adam Adli.

Adam, an UPSI student, has been charged with disciplinary action by the university for replacing a flag depicting the Prime Minister’s face with a banner proclaiming academic freedom two weeks ago.

The police, with the participation of the Federal Reserve Units, made their move to disperse the students at about 2.30am, in the process arresting at least 17 students, including Adam Adli.

The students had earlier lied down on the road when the police made their move to disperse the protesting crowd.

Two of the students were arrested while making a police report, and one for shouting at the police to release the arrested students. The arrested students are all being held at the Tanjung Malim police station.

Students also claimed that the police acted in a brutal manner in dispersing them, as a result causing injuries to some students.

Some eye-witnesses said that one student, Muhammad Safwan Anang, was allegedly assaulted by at least eight police personnel.

Muhammad Safwan, a student leader, had been admitted to the Slim River Hospital in a serious condition, including suffering from a broken cheekbone.

Calls for release

The police came under severe condemnation for the heavy tactics against the students.

Lawyers For Liberty’s Fadiah Nadwa Fikri said the police had unlawfully used excessive force against peaceful and unarmed students.

She urged the authorities to immediately release the arrested students and take action against the police officers who had been involved in using excessive force against the students.

Meanwhile PKR’s communications director Nik Nazmi Nik Ahmad also criticised the police over their actions.

“This violence makes a mockery of the Prime Minister’s Malaysia Day speech and so-called Transformation Agenda,” he said, referrring to Najib Tun Razak’s promise of political reforms.

Alhamdulillah, some of the student who had been arrested were released yesterday evening. I'm sure, this is not the end point of their battle. This experience will make them much strongest. May Allah keep their spirit for the betterment of next generation. Allahu Akbar!!!