To multiply any whole number by
5:Add one zero at the end of the number and divide by 2
10 or power of 10:Add the same number of zero at the end of the number
20:Multiply by 100 and divide by 5
25:Multiply by 100 and divide by 4
9,99,999...:Multiply by 10,100,1000 and subtract the original number.e.g
54×99=54×100-54=5346
11:Multiply by 10 and add the original number,e.g
153×11=(153×10)+153=1683
If you are confused just comment below
No comments:
Post a Comment