Concept: Multiplication Tricks

 

Instead of multiplying with 5, multiply with 10 and then divide by 2.

Instead of multiplying with 25, multiply with 100 and then divide by 4.

Instead of multiplying with 125, multiply with 1000 and then divide by 8.

 

Assume a zero at the beginning and at the end of the number. Now add two digits at a time starting with right most two digits and write them as single digit integer. Carry forward if there is any.

 

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