Video: Subtracting One-Digit Numbers from Two-Digit Numbers by Decomposing a Ten

Olivia used place value blocks to show that 73 is 7 tens and 3 ones. She wants to take away 9 from 73, but there are not enough ones. Pick another way she could make 73 so she can take away 9 ones.

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Video Transcript

Olivia used place value blocks to show that 73 is seven tens and three ones. She wants to take away nine from 73, but there are not enough ones. Pick another way she could make 73 so she can take away nine ones.

The question tells us that Olivia wants to take away nine from 73. But she only has three ones. She needs to make 73 in a different way so that she can take away nine ones.

To do this, Olivia could take a tens block from the tens column and exchange it for 10 ones. So she has enough ones to take away nine. So Olivia had seven tens. She took away one, which means she now has six tens. She exchanged or swapped the tens block for 10 ones. Now, she has 13 ones instead of three and she has enough ones to take away nine.

This model shows another way that Olivia could make 73 so that she can take away nine ones.

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