Alright, let's solve this math problem step by step. First, we have the number 729. Next, we see the multiplication sign, which means we need to multiply something. And what are we multiplying it by? We multiply it by 18. So, we're going to take the number 729 and add it to itself 18 times.
Step 1: 0 + 729 = 729
Step 2: 729 + 729 = 1458
Step 3: 1458 + 729 = 2187
Step 4: 2187 + 729 = 2916
Step 5: 2916 + 729 = 3645
Step 6: 3645 + 729 = 4374
Step 7: 4374 + 729 = 5103
Step 8: 5103 + 729 = 5832
Step 9: 5832 + 729 = 6561
Step 10: 6561 + 729 = 7290
Step 11: 7290 + 729 = 8019
Step 12: 8019 + 729 = 8748
Step 13: 8748 + 729 = 9477
Step 14: 9477 + 729 = 10206
Step 15: 10206 + 729 = 10935
Step 16: 10935 + 729 = 11664
Step 17: 11664 + 729 = 12393
Step 18: 12393 + 729 = 13122

So, 729*18 = 13122