Three plus what plus six equals 16.
The total of our sum is 16. And we can break 16 into two parts, a 10 and six. We already have a six in our number sentence. So we need to work out what to add to three to make 10 because 10 plus six is 16. We could use ten frames to help us work out what we need to add to three to make 10. One, two, three, four, five, six, seven. Three plus seven makes 10. Then, we have the six to give us a total of 16.
Three plus seven plus six equals 16.