Video: Using Arrays to Find the Missing Number in a Division Equation

Find the missing number. _ ÷ 3 = 9.

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Video Transcript

Find the missing number. Something divided by three equals nine.

In this problem, we’re given a division number sentence, but with a missing number at the start. How can we find out what the missing number is? As well as the number sentence, we’re given an array of dots.

So let’s use the array to help us find out what the missing number is. The array has three rows, and there are nine in each row.

And so, if we split the whole amount into three equal rows, we will have nine in each row. This is the same as our division. The missing number is the whole amount. The number three is the number of rows. And the number nine is the amount of dots that we have in each row.

So let’s use what we know to find the whole amount. What are three rows of nine? One times nine is nine. Two times nine is 18. And so, three rows of nine is 27.

And so our missing number is 27. 27 divided by three equals nine.

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