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Video: Finding a Missing Factor in a Multiplication Equation Relating Three Whole Numbers

Kerrie Lynskey

Find the missing factor. 20 = ? × 4.


Video Transcript

Find the missing factor: 20 equals an unknown number multiplied by four.

The keyword here is factor. Factors are the numbers that we multiply together to make a given number. So in the given example, two multiplied by four equals eight. Two and four are factors of eight.

We need to find the factors of 20. Four is given. We have to find the missing factor or, in other words, a number which we can multiply by four to make 20.

The quickest and easiest way to work out the answer is to use skip counting to help. We need to count in fours. Here we go! Four, eight, 12, 16, 20. Four, eight, 12, 16, 20.

How many times did we skip count in fours? That’s five! So five times four equals 20. Five and four are factors of 20. The missing factor is five.