Trick No. 2 – Dividing with Zeros

Numbers ending in zeros are just multiples of ten (or one hundred, or one thousand…) To divide with a number ending in zeros, ignore the zeros, do your division, then cancel the same number of zeros from the left and the right of the problem*

Example: 4800 ÷ 120
Remove all zeros and perform 48 ÷ 12 = 4
Count the number of zeros on the left and right of the origianl problem: two on the left, one on the right
Cancel one zero from each side of the original problem and add one zero to the result.
Answer: 40

Example: 4800 ÷ 1200
Remove all zeros and perform 48 ÷ 12 = 4
Count the number of zeros on the left and right of the origianl problem: two on the left, two on the right
Cancel two zeros from each side of the original problem and add two zeros to the result.
Answer: 400

Example: 48,000 ÷  120,000 – THIS IS A TRICKY ONE!
Remove all zeros and perform 48 ÷ 12 = 4
Count the number of zeros on the left and right of the origianl problem: three on the left, four on the right
Cancel three zeros from each side of the original problem and add one zero to the result.
Answer: 40?

*BUT: 120,000 is BIGGER than 48,000, so this answer doesn’t make sense. Instead of adding and removing zeros, we can talk about places. In this case, instead of adding one zero (moving one place to the right) we have to move one place to the left. Answer: 0.4. We’ll discuss this type of problem again in a later trick.