OK, let's crack this. We're given 731 and our task is to multiply it by 18. Essentially, we'll be adding 731 to itself 18 times.
Step 1: 0 + 731 = 731
Step 2: 731 + 731 = 1462
Step 3: 1462 + 731 = 2193
Step 4: 2193 + 731 = 2924
Step 5: 2924 + 731 = 3655
Step 6: 3655 + 731 = 4386
Step 7: 4386 + 731 = 5117
Step 8: 5117 + 731 = 5848
Step 9: 5848 + 731 = 6579
Step 10: 6579 + 731 = 7310
Step 11: 7310 + 731 = 8041
Step 12: 8041 + 731 = 8772
Step 13: 8772 + 731 = 9503
Step 14: 9503 + 731 = 10234
Step 15: 10234 + 731 = 10965
Step 16: 10965 + 731 = 11696
Step 17: 11696 + 731 = 12427
Step 18: 12427 + 731 = 13158

So, 731*18 = 13158