Scarlett added nine and seven by
making 10. What number is missing from her
solution? Nine plus seven equals 16. 10 plus what equals 16.
To understand what Scarlett’s done
here, we could try to answer the question ourselves. And we’re going to try to make the
addition, nine plus seven, a little easier to work out by making 10. Here’s what nine plus seven might
look like using two ten frames. And one way to find the answer, we
could start with the number nine and then count on seven more. But you know, adding a number to
the number 10 is always a quick way to find the total. So what we can do to help ourselves
is to turn the number nine into 10.
What goes with nine to make 10? Well, we know nine plus one more
makes 10. To find the extra one that we need,
we’re going to split our number seven up into one and whatever is left. And we know that one and six make
seven. We can show this using our ten
frames by moving across one counter. Now, we’ve made 10 in the first ten
frame. We just need to add the six
counters in the second ten frame. We’ve turned our calculation nine
plus seven into 10 plus six. 10 plus six is 16. And so we know that nine plus seven
must be 16 too. Scarlett added nine and seven by
making 10. The number that’s missing from her
solution is the number six. 10 plus six equals 16.