OK, let's work through this together. We're starting with 794 and we're going to multiply it by 15, which means we add 794 to itself 15 times.
Step 1: 0 + 794 = 794
Step 2: 794 + 794 = 1588
Step 3: 1588 + 794 = 2382
Step 4: 2382 + 794 = 3176
Step 5: 3176 + 794 = 3970
Step 6: 3970 + 794 = 4764
Step 7: 4764 + 794 = 5558
Step 8: 5558 + 794 = 6352
Step 9: 6352 + 794 = 7146
Step 10: 7146 + 794 = 7940
Step 11: 7940 + 794 = 8734
Step 12: 8734 + 794 = 9528
Step 13: 9528 + 794 = 10322
Step 14: 10322 + 794 = 11116
Step 15: 11116 + 794 = 11910

So, 794*15 = 11910