Math without a Calculator

For mulitplying number close to 10

Step 1. Add the difference between one of the numbers and 10, then multiply it by the other number. This gives you the leading 2 numbers.

Step 2-The last number is the multiple of the ones digits. NOTE-if this multiple is greater than 10 you will have to carry the first number forward.

Problem	Answer
14 x 13=	=?
Step 1--> 13-10=3	=?
Step 1A--> 14 +3=17	=17_
Step2--> 4x3=12	=1(7+1) 2
	=182

For mulitplying number close to but below 100

Step 1 Find the difference of both numbers from 100

Step 2 Subtract the difference of the second number from the first and this is your first 2 numbers.

Step 3 multiply the 2 differences to get the final 2 places

95 x 97=?

Differences -5 and -3	=?
Subtract 3 from 95 = 92	= 9 2 _ _
Multiply the differences 5 x 3=15	= 9 2 1 5
	=9215

For mulitplying number by 11

Step 1-Add the 2 numbers that are multipled by 11 and place that number between them. NOTE if the sum is greater than 9 you must carry the first number forward.

14 x 11=?

Separate the numbers	1 _ 4
Add them and place in the middle	1 5 4

More complicated

47 x 11=?

Separate the numbers	4 _ 7
add the 2 numbers =11	(4 + 1) 1 7
Note 11 breaks up to 1 and 1, carry the first 1 forward	=517

Squaring Numbers 11-19

Step 1-Add the units place to the entire number to get the first 2 digits

Step 2- square the last number NOTE if the sum is greater than 9 you must carry the first number forward.

17²=?

Add the units place to 7 + 17	=24 _
Square the last number 7 x7 =49 (break up 49)	= 2 (4 +4) 9
	=289

For mulitplying number by 11

Step 1-Add the 2 numbers that are multipled by 11 and place that number between them. NOTE if the sum is greater than 9 you must increase the Hundreds number accordingly