TRICKY MATH
Math Tricks for kids
1. Multiplying by 6
If you multiply 6 by an even number, the answer will end with the same digit. The number in the ten's place will be half of the number in the one's place.This ploy works effortlessly and students can add it to their collection of maths magic tricks!
2. The Answer Is 2
Think of a number.
Multiply it by 3.
Add 6.
Divide this number by 3.
Subtract the number from Step 1 from the answer in Step 4.
The answer is 2
3. Same Three-Digit Number
Think of any three-digit number in which each of the digits is the same. Examples include 333, 666, 777, and 999.
Add up the digits.
Divide the three-digit number by the answer in Step 2.
The answer is 37.
4. Six Digits Become Three
Take any three-digit number and write it twice to make a six-digit number. Examples include 371371 or 552552.
Divide the number by 7.
Divide it by 11.
Divide it by 13.
The order in which you do the division is unimportant!
The answer is the three-digit number.
5. The 11 Rule
The 11 rule is one of those magic tricks and methods that can be used to quickly multiply two-digit numbers by 11 in your head.
Separate the two digits in your mind.
Add the two digits together.
Place the number from Step 2 between the two digits. If the number from Step 2 is greater than 9, put the one's digit in the space and carry the ten's digit.
6. Memorizing Pi
This is probably the most fun tricks in maths -to remember the first seven digits of pi, count the number of letters in each word of the sentence:
"How I wish I could calculate pi."
This becomes 3.141592.
7. Contains the Digits 1, 2, 4, 5, 7, 8
Select a number from 1 to 6.
Multiply the number by 9.
Multiply it by 111.
Multiply it by 1001.
Divide the answer by 7.
The number will contain the digits 1, 2, 4, 5, 7, and 8.
8. Multiply Large Numbers in Your Head
Another math magic tricks and methods to apply to easily multiply two double-digit numbers, is to use their distance from 100 to simplify the math:
Subtract each number from 100.
Add these values together.
100 minus this number is the first part of the answer.
Multiply the digits from Step 1 to get the second part of the answer.
You've got 210 pieces of pizza and want to know whether or not you can split them evenly within your group. Rather than taking out the calculator, use these simple shortcuts to do the math in your head:
Divisible by 2 if the last digit is a multiple of 2 (210).
Divisible by 3 if the sum of the digits is divisible by 3 (522 because the digits add up to 9, which is divisible by 3).
Divisible by 4 if the last two digits are divisible by 4 (2540 because 40 is divisible by 4).
Divisible by 5 if the last digit is 0 or 5 (9905).
Divisible by 6 if it passes the rules for both 2 and 3 (408).
Divisible by 9 if the sum of the digits is divisible by 9 (6390 since 6 + 3 + 9 + 0 = 18, which is divisible by 9).
Divisible by 10 if the number ends in a 0 (8910).
Divisible by 12 if the rules for divisibility by 3 and 4 apply.
10. Finger Multiplication Tables
Everyone knows you can count on your fingers. Did you realize you can use them for multiplication? A simple maths magic trick to do the "9" multiplication table is to place both hands in front of you with fingers and thumbs extended. To multiply 9 by a number, fold down that number finger, counting from the left.