Without delay, let's solve this. We've got 1 and we will be multiplying it by 15, that is, adding 1 to itself 15 times.
Step 1: 0 + 1 = 1
Step 2: 1 + 1 = 2
Step 3: 2 + 1 = 3
Step 4: 3 + 1 = 4
Step 5: 4 + 1 = 5
Step 6: 5 + 1 = 6
Step 7: 6 + 1 = 7
Step 8: 7 + 1 = 8
Step 9: 8 + 1 = 9
Step 10: 9 + 1 = 10
Step 11: 10 + 1 = 11
Step 12: 11 + 1 = 12
Step 13: 12 + 1 = 13
Step 14: 13 + 1 = 14
Step 15: 14 + 1 = 15

So, 1*15 = 15