You do 5625 / 25 like this: For each step you multiply 25 by the highest number possible in the first 2 numbers. So if it was 27 / 9 you would find how many times 9 can fit into 27 but since the number 5625 is not one of the first 10 multiples of 25 you see the first 2 numbers and if you still can't divide you combine the next value. The top number is the answer.