He could give each grandchild 3 cookies each. He would then have 12 cookies remaining.
You would divide 60 by 16 which would be 3 with a remainder of 12. The remainder is the number of cookies left after giving each grandchild the same amount of cookies each.
I hope this helps!
Step-by-step explanation:

Answer:
It is important so we don't make the equation untrue
Step-by-step explanation:
If you don't balance the equation the two sides of the equation will not equal each other and make the equation untrue