OK, let's work through this together. We're starting with 513 and we're going to multiply it by 15, which means we add 513 to itself 15 times.
Step 1: 0 + 513 = 513
Step 2: 513 + 513 = 1026
Step 3: 1026 + 513 = 1539
Step 4: 1539 + 513 = 2052
Step 5: 2052 + 513 = 2565
Step 6: 2565 + 513 = 3078
Step 7: 3078 + 513 = 3591
Step 8: 3591 + 513 = 4104
Step 9: 4104 + 513 = 4617
Step 10: 4617 + 513 = 5130
Step 11: 5130 + 513 = 5643
Step 12: 5643 + 513 = 6156
Step 13: 6156 + 513 = 6669
Step 14: 6669 + 513 = 7182
Step 15: 7182 + 513 = 7695

So, 513*15 = 7695