This is the continuation of my previous post
Multiply any two digit number by 11
Example 1:
72 x 11 = 792
Step 1: Split the two digit number and add space between it 7 _ 2
Step 2: Now fill the space by summing 7 & 2 so it will become like 7 9 2. So the answer is 792
Example 2:
67 x 11 = 737
Step 1: Split the two digit number and add space between it 6 _ 7
Step 2: Now fill the space by adding 6 & 7 so it will become like 6 13 7.
Step 3: Here sum of two digits is 13 so carry forward the 1 to the left side so it will become like 7 3 7. Now the answer is 737.
Multiply by 5
To quickly multiply any number by 5 follow the below technique
Example 1:
62 x 5 = 310
Step 1: Divide the number by 2. Here 62/ 2 is 31
Step 2: Now multiply by 10. Here 31 x 10 = 310 so is the answer
Here the concept is number 5 is equal to 10/2 and if you notice here I am dividing the 62 by 2 & multiplying by 10
Example 2:
35 x 5 = 175
Step 1: Divide the number by 2. Here 35/ 2 is 17.5
Step 2: Now multiply by 10. Here 17.5 x 10 = 175 so is the answer 🙂
Multiply by doubling & halving
Here is the another technique for multiplying numbers
Example 1:
70 x 8 = 560
Step 1: Here I am going to double the first number & halve the second number so it becomes 140 x 4
Step 2: Repeat the previous step again so now becomes 280 x 2. Since cannot repeat the same step and even if you do the result is still same 560
This trick works best when halving number is even number else you may end up with decimal numbers