After a homework check and bell work, we reviewed multiplying and dividing by 10, 100, 1000, 10 000 etc. and decided on some rules to help us perform these operations. We came up with the rules below (please note – later on in the year we will cover this again and explain it in terms of moving the decimal place).
Rule for multiplying by 10, 100, 1000, etc.
When you are multiplying you add as many zeroes to the product as there are in the factor if the factor is a multiple of 10 (10, 100, 1000, 10 000, etc)
Ex. 800 x 1 000 000 = 800 000 000
15 x 100 = 1500
Rule for dividing by 10, 100, 1000, etc.
When you are dividing a number that is a multiple of 10, 100, 1000, etc. (ex. has several zeroes at the end - 3400, 57 000,
99 000 000, etc.) by a multiple of 10 (10, 100, 1000, etc.), remove the number of zeros that are in your divisor.
Ex. 2 000 000 ÷ 100 = 20 000
700 000 000 ÷ 1000 = 700 000
