Here are some neat math tricks!

Here are some tricks for math that will help you save time. If you want to multiply two numbers by two numbers, there are several things you can do to make it a less daunting task.

 

If you multiply a number by 11, all you have to do is add the 2 digits of the other number. For example, multiply 11 by 18. You don’t have to actually do it step by step. You can cheat. Add 1 and 8 and you get 9. You multiply the first digit of the first number by the first digit of the second number (1×2=2), and you multiply the second digit of the first number by the second digit of the second number. In this case, that would be 1 times 8, or 8. To get the middle number, you add the two numbers, 1 and 8, to get 9. So the answer is 198.

 

Let’s try another example. 11 times 23. You multiply 1 x 2, to get the first number of 2. You multiply 1 x 3 which is 3. Then for the middle number you add 2 + 3, which is 5. Therefore, the answer is 253. See how easy it is?

 

Those examples work best when your first number begins with 1. But of course most times it’s not going to. So let’s try a different example. 23 x 69. 69 is close to 70, so instead of multiplying 23 by 69, multiply 23 by 70. That gets you 1610. It only takes a couple of seconds to do that but you still have 2 more steps to do. 70-69 is 1. Multiply 1 by 23 and then subtract 23 from 1710 and you will have your answer. 1710 minus 23 equals 1687. This will take a little more practice than the first example, but soon you will be able to do this faster than a calculator and impress all of your friends!

 

Let’s try a second example of the harder type. 14 multiplied by 58. 14 times 60 is 840. To get 58, u must subtract 2 from 60. 2 times 14 is 28. Subtract 28 from 840 and you get 812.

 

If you are writing a finance exam, these simple tricks will save you time and in a case like that, every second helps! Or if you are at a party and want to impress your friends, you can compete with a calculator that someone brings! It’s fun.

 

 

 

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2 Comments

  • SC

    Reply Reply November 3, 2012

    Different people have different tricks. When I want to multiply a desired number by 11, I first multiply it by 10, then add the result to the desired number.

    What is 18*11?

    18*10=180 (that’s easy to do, just add a zero)
    180+18=198

    What is 47*11?

    47*10= 470 (easy do to again, just add a zero to the end)
    470+47=517

    What is 98*11?

    98*10= 980
    980+98=1078

    Works easily if your desired number has two digits in it. But this methods assumes that you are good at adding numbers.

    • admin

      Reply Reply November 3, 2012

      Yes numbers are neat! I love doing stuff like this. Anything that saves time is awesome. If you know any more tricks, feel free to share!

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