Multiplying any 2 digit numbers together by mere mental arithmetic!
GTFT5TF7CZDTAn easy way to multiply a 2 digit number by a 2 digit number using Rainbow Multiplication.
Step-1: Multiply the ones digit of both the numbers together and write down the ones; carry, if any. This gives the first figure of the answer.
Step-3: Multiply the tens digit of both the numbers together and add carried digit; write it down.
Example: 12 x 23
So the answer is 276.This is done using the VERTICALLY AND CROSSWISE formula; also called Rainbow Multiplication.
- 21 x 23 = 483
We first put, or imagine, 23 below 21:
There are 3 steps:
b) Multiply crosswise and add: 2 x 3 + 1 x 2 = 8. This gives the middle figure.
c) Multiply vertically on the right: 1 x 3 = 3. This gives the last figure of the answer.
- 6 x 3 = 18; 6 x 1 + 1 x 3 = 9; 1 x 1 = 1
There were no carries in the method given above. However, there only involve one small extra step, if there is any carries in any place.
The method is the same as above except that we get a 2-figure number, 14, in the middle step, so the 1 is carried over to the left (4 becomes 5).
So, 21 × 26 = 546
- 33 x 44 = 1452
Then vertically on the right we get 12 and the 1 here is carried over to the 144 to make 1452.