OK, let's crack this. We're given 847 and our task is to multiply it by 15. Essentially, we'll be adding 847 to itself 15 times.
Step 1: 0 + 847 = 847
Step 2: 847 + 847 = 1694
Step 3: 1694 + 847 = 2541
Step 4: 2541 + 847 = 3388
Step 5: 3388 + 847 = 4235
Step 6: 4235 + 847 = 5082
Step 7: 5082 + 847 = 5929
Step 8: 5929 + 847 = 6776
Step 9: 6776 + 847 = 7623
Step 10: 7623 + 847 = 8470
Step 11: 8470 + 847 = 9317
Step 12: 9317 + 847 = 10164
Step 13: 10164 + 847 = 11011
Step 14: 11011 + 847 = 11858
Step 15: 11858 + 847 = 12705

So, 847*15 = 12705