OK, let's crack this. We're given 126 and our task is to multiply it by 12. Essentially, we'll be adding 126 to itself 12 times.
Step 1: 0 + 126 = 126
Step 2: 126 + 126 = 252
Step 3: 252 + 126 = 378
Step 4: 378 + 126 = 504
Step 5: 504 + 126 = 630
Step 6: 630 + 126 = 756
Step 7: 756 + 126 = 882
Step 8: 882 + 126 = 1008
Step 9: 1008 + 126 = 1134
Step 10: 1134 + 126 = 1260
Step 11: 1260 + 126 = 1386
Step 12: 1386 + 126 = 1512

So, 126*12 = 1512