Let's get this math done. We have 502 and we're going to multiply it by 15. This is the same as taking 502 and adding it to itself 15 times.
Step 1: 0 + 502 = 502
Step 2: 502 + 502 = 1004
Step 3: 1004 + 502 = 1506
Step 4: 1506 + 502 = 2008
Step 5: 2008 + 502 = 2510
Step 6: 2510 + 502 = 3012
Step 7: 3012 + 502 = 3514
Step 8: 3514 + 502 = 4016
Step 9: 4016 + 502 = 4518
Step 10: 4518 + 502 = 5020
Step 11: 5020 + 502 = 5522
Step 12: 5522 + 502 = 6024
Step 13: 6024 + 502 = 6526
Step 14: 6526 + 502 = 7028
Step 15: 7028 + 502 = 7530

So, 502*15 = 7530