Fill in the blank: 10 take away
seven equals what. And then fill in the blank: 15 take
away seven equals what.
This question has two parts. And did you notice? They’re linked. In both parts, we need to take away
seven. In the first part, we’re asked to
start with 10 and take away seven. But then, in the second part, we
need to find the answer to 15 take away seven. And why do you think we’re given
two similar calculations like this one after another? Do you think maybe the first
calculation might help us find the answer to the second? Let’s find out. Now there’s a reason why we don’t
have a 10 frame to help us with this first question because taking away numbers from
10 is quite quick and easy to do. We just need to remember the facts
we know about the numbers that go together to make 10.
Now do you remember what goes
together with seven to make 10? We know that seven and three makes
10. And so if we start with 10 and take
away seven, we’re going to be left with three. So if 10 take away seven equals
three, how could we use this to help us find the answer to 15 take away seven. Well, this is where our 10 frames
come in useful because they help us to see that the number 15 is made up of 10 and
five ones. And so if we want to take away
seven from 15 really quickly, we can just start by looking at this one 10 because we
know how to take away seven from 10 really quickly. As we’ve said already, 10 take away
seven is going to leave us with three.
So to find the answer to 15 take
away seven, we just need to add the three ones that we’ve got left with the five
ones over here. And we know that three plus another
five equals eight altogether. And that’s how we know that 15 take
away seven equals eight. We’ve used a fact to do with
subtracting from 10 to help us take away from a teen number. 10 take away seven equals
three. And so we know that 15 take away
seven equals eight.