Question Video: Subtracting One-Digit Numbers Using a Related Addition Sentence Mathematics • 1st Grade

Liam had 9 toy cars. He lost 3 of the cars. He can work out how many are left by completing either of the following number sentences: 9 − 3 = _, 3 + _ = 9. How many cars are left?

02:00

Video Transcript

Liam had nine toy cars. He lost three of the cars. He can work out how many are left by completing either of the following number sentences. Nine take away three equals what. Three plus what equals nine. How many cars are left?

This is a subtraction problem. We know that Liam had nine toy cars and he lost three of them. We have to work out how many cars he has left. This part–whole model helps us think about how to solve the problem. We know the whole amount or the number of cars Liam had to begin with is nine. We know that one of the parts or one of the numbers that go together to make nine is the number three because Liam lost three of the cars. So one way we could find out how many cars Liam has left is to subtract the three that he lost from the nine he had to begin with.

This is where the 10 frame becomes really useful. There are nine cars in the 10 frame, and three of them have been crossed out because we know that Liam lost three of his cars. How many cars are there left? In other words, what is nine take away three? It’s six. There are six cars left in the 10 frame, so we know that three and six are the two numbers that go together to make nine. If nine take away three is six, then three plus six equals nine because three and six are a pair of numbers which go together to make nine. If Liam had nine toy cars and he lost three of them, he has six cars left.

Nagwa uses cookies to ensure you get the best experience on our website. Learn more about our Privacy Policy.