You only need to write the problem on each box. However, you need to solve each problem so that you will know which box to put the problem to. In the event that there is a follow up question on how you came to the decision of putting certain problem in a box, then you can show your solutions as proof.
Box 1 will have Problem 2
Box 2 will have Problem 3 (assuming that 5413 is actually 541.3)
Box 3 will have Problem 1
Proof:
Problem 2: 45 * 22 = 990 answer is less than 1000
Problem 3: 458.7 + 541.3 = 1000 answer is equal to 1000
Problem 1: 8657 / 8 = 1082.125 answer is more than 1000