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 NeedWillingness to think out of the box!
Multiply ANY number by 11 rapidly.
Say 53 x 11.
Write both numbers, 5 and 3, leaving a space between them.
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!
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.
EXAMPLE: 75x75 -> 7x8=56, add 25. Answer 5625
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
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!