OK, let's work through this together. We're starting with 617 and we're going to multiply it by 15, which means we add 617 to itself 15 times.
Step 1: 0 + 617 = 617
Step 2: 617 + 617 = 1234
Step 3: 1234 + 617 = 1851
Step 4: 1851 + 617 = 2468
Step 5: 2468 + 617 = 3085
Step 6: 3085 + 617 = 3702
Step 7: 3702 + 617 = 4319
Step 8: 4319 + 617 = 4936
Step 9: 4936 + 617 = 5553
Step 10: 5553 + 617 = 6170
Step 11: 6170 + 617 = 6787
Step 12: 6787 + 617 = 7404
Step 13: 7404 + 617 = 8021
Step 14: 8021 + 617 = 8638
Step 15: 8638 + 617 = 9255

So, 617*15 = 9255