Without delay, let's solve this. We've got 539 and we will be multiplying it by 15, that is, adding 539 to itself 15 times.
Step 1: 0 + 539 = 539
Step 2: 539 + 539 = 1078
Step 3: 1078 + 539 = 1617
Step 4: 1617 + 539 = 2156
Step 5: 2156 + 539 = 2695
Step 6: 2695 + 539 = 3234
Step 7: 3234 + 539 = 3773
Step 8: 3773 + 539 = 4312
Step 9: 4312 + 539 = 4851
Step 10: 4851 + 539 = 5390
Step 11: 5390 + 539 = 5929
Step 12: 5929 + 539 = 6468
Step 13: 6468 + 539 = 7007
Step 14: 7007 + 539 = 7546
Step 15: 7546 + 539 = 8085

So, 539*15 = 8085