OK, let's work through this together. We're starting with 812 and we're going to multiply it by 17, which means we add 812 to itself 17 times.
Step 1: 0 + 812 = 812
Step 2: 812 + 812 = 1624
Step 3: 1624 + 812 = 2436
Step 4: 2436 + 812 = 3248
Step 5: 3248 + 812 = 4060
Step 6: 4060 + 812 = 4872
Step 7: 4872 + 812 = 5684
Step 8: 5684 + 812 = 6496
Step 9: 6496 + 812 = 7308
Step 10: 7308 + 812 = 8120
Step 11: 8120 + 812 = 8932
Step 12: 8932 + 812 = 9744
Step 13: 9744 + 812 = 10556
Step 14: 10556 + 812 = 11368
Step 15: 11368 + 812 = 12180
Step 16: 12180 + 812 = 12992
Step 17: 12992 + 812 = 13804

So, 812*17 = 13804