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How to learn some easy, rapid Math Tricks

By Edited Jul 4, 2015 3 4


Fun, easy to learn ways to solve normally difficult math problems in your head! Learning math in school was NEVER this easy! This would have made math class soooo easy.
Read on for a couple of cool tricks...

Things You Will Need

Willingness to think out of the box!

Step 1

Multiply ANY number by 11 rapidly.



Say 53 x 11.


Write both numbers, 5 and 3, leaving a space between them.
5 3

Add both numbers together for the middle number.
5 5+3 3
or 583

Answer is 583!

For a two digit middle answer, CARRY THE TENS OVER TO THE FIRST NUMBER.

example 76 x 11
7 6 add them together for 13:
7 13 6 Since the logical thing tells us the answer 7136 is too large a number, we must convert the 13. The three remains between the seven and six and the one then adds to the seven. Thus 836!



Step 2

Square any number ending in 5 rapidly.


Say 652 or 65 x 65


multiply the tens digit by the next number.
6, or Sixty, is in the tens place, so multiply the tens place, 6, by the next higher number. Seven follows six, so...
Example: 6 x 7 = 42

Always add 25 to the answer
Add 25 behind the answer of 42.
Answer 4225.

EXAMPLE: 75x75 -> 7x8=56, add 25. Answer 5625


Answer 4225.

Step 3

Multiply any number by 25.

(A reciprocal problem)

Say 28 x 25



Divide the number (28) by four -- 28 divided by 4 equals 7

Estimate how large answer should be, (should be in the 100's)

Add zeroes to the previous answer. 7, add two zeroes, equals 700

28 x 25 -> 28 divided by 4 -> 7 -> add zeroes -> 700

EXAMPLE 2:

420 x 2.5 (disregard the decimal)

Divide by four 420 divided by 4 equals 105 (decimals dropped)

Estimate the answer - should be around 1000.

Drop the decimal and an a zero. Answer 1050

420 x 2.5 -> 420 divided by 4 -> 105 -> add zeroes -> 1050












While these tricks may seem a little complicated, with practice they become a piece of cake. For more information about and really great tips on Math, check out Rapid Math Tricks and Tips. It's a fascinating book!

Tips & Warnings


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Comments

Nov 18, 2009 4:07pm
jcmayer777
I tried it, and they actually worked. Very nice article. I'm giving a thumbs up, since I was really skeptical, but proven wrong.
Feb 28, 2010 10:59am
sound_foundation
This is great, I was a math major in college, but never learned these "tricks" growing up. Very interesting.
Dec 7, 2011 6:35pm
McGivneyC
I've heard of some of these nifty tricks, i just tend to forget how they work... :)
Jun 16, 2013 6:47pm
BritheMathGuy
cool stuff
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