OK, let's crack this. We're given 918 and our task is to multiply it by 15. Essentially, we'll be adding 918 to itself 15 times.
Step 1: 0 + 918 = 918
Step 2: 918 + 918 = 1836
Step 3: 1836 + 918 = 2754
Step 4: 2754 + 918 = 3672
Step 5: 3672 + 918 = 4590
Step 6: 4590 + 918 = 5508
Step 7: 5508 + 918 = 6426
Step 8: 6426 + 918 = 7344
Step 9: 7344 + 918 = 8262
Step 10: 8262 + 918 = 9180
Step 11: 9180 + 918 = 10098
Step 12: 10098 + 918 = 11016
Step 13: 11016 + 918 = 11934
Step 14: 11934 + 918 = 12852
Step 15: 12852 + 918 = 13770

So, 918*15 = 13770