For the walls of the house John would use large planks of wood. Each plank needs 9 pieces of nails to be secured and he would use 37 planks. How many nails does John need for the house wall?
There are 37 planks. 
Each plank needs 9 nails. 
So we multiply 37 by 9 to get the total number of nails that John needs for the walls of the house. 

37 * 9 = 333 nails