Sure thing! We've got 615 and we're gonna multiply it by 15. That's the same as adding 615 to itself 15 times.
Step 1: 0 + 615 = 615
Step 2: 615 + 615 = 1230
Step 3: 1230 + 615 = 1845
Step 4: 1845 + 615 = 2460
Step 5: 2460 + 615 = 3075
Step 6: 3075 + 615 = 3690
Step 7: 3690 + 615 = 4305
Step 8: 4305 + 615 = 4920
Step 9: 4920 + 615 = 5535
Step 10: 5535 + 615 = 6150
Step 11: 6150 + 615 = 6765
Step 12: 6765 + 615 = 7380
Step 13: 7380 + 615 = 7995
Step 14: 7995 + 615 = 8610
Step 15: 8610 + 615 = 9225

So, 615*15 = 9225