Find the missing number. 15 take away the missing number is equal to 13 take away four.
We can use a number line to help work out 13 take away four. We need to start at 13 and count backward four. 13 take away four is nine. We know that this part of the equation equals nine because 13 take away four is nine.
Now we need to work out what to take away from 15 to make nine. And we can use the number line to help us. Let’s start at 15 and count back until we get to nine. One, two, three, four, five, six. 15 take away six equals nine.