Alright, let's solve this math problem step by step. First, we have the number 561. Next, we see the multiplication sign, which means we need to multiply something. And what are we multiplying it by? We multiply it by 15. So, we're going to take the number 561 and add it to itself 15 times.
Step 1: 0 + 561 = 561
Step 2: 561 + 561 = 1122
Step 3: 1122 + 561 = 1683
Step 4: 1683 + 561 = 2244
Step 5: 2244 + 561 = 2805
Step 6: 2805 + 561 = 3366
Step 7: 3366 + 561 = 3927
Step 8: 3927 + 561 = 4488
Step 9: 4488 + 561 = 5049
Step 10: 5049 + 561 = 5610
Step 11: 5610 + 561 = 6171
Step 12: 6171 + 561 = 6732
Step 13: 6732 + 561 = 7293
Step 14: 7293 + 561 = 7854
Step 15: 7854 + 561 = 8415

So, 561*15 = 8415