Multiply by OneMultiplying by one is very easy and there is nothing new here but it is included here for completeness. For any number multiplied by one the answer is always the same number as you started with. In the multiplication you just copy the number down.

The Rule For Multiplying By One

  1. Copy each digit in the number.

An Example - Multiplying 628 By 1


We will have a look at 628 x 1 and we will set it up the same as we have done for all the previous calculations.
Multiplying by one Example 1 Setup

Step 1
We again shrink our red box to cover just the digit we are looking at as we do not need to worry about the neighbor.
We are on the number 8 and we just copy that down to the answer.Multiplying by ten Example 1 Step 2

Step 2
Moving to the left we are now looking at 2 and we again just copy that down to our answer.Multiplying by ten Example 1 Step 2

Step 3
Moving again to the left we are now looking at 6 which we copy down to the answer.Multiplying by two Example 1 Step 3

Last Step
This step can be ignored as we are over the leading zero and there is no need to copy the zero as leading zeros do not change the number. The answer is 628 which is the same number we started with.Multiplying by ten Example 1 Last Step

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