Michael had 17 buttons. Pile A had ten ones. How many are in pile B?
We know that Michael has 17 buttons. And he’s placed 10 of them into pile A. We need to work out how many buttons that should be in pile B. If we add a button to pile B, there will be 11 buttons. If we add another button, there’ll be 12. Now, we have three ones in pile B, which means we have 13 buttons add one more makes 14, 15. Now, we’ve added six buttons; we have 16 altogether. One more button makes 17. Pile A has ten ones. Pile B has seven ones. 10 and seven makes 17. Pile A had ten ones. There are seven in pile B.