Sure thing! We've got 903 and we're gonna multiply it by 18. That's the same as adding 903 to itself 18 times.
Step 1: 0 + 903 = 903
Step 2: 903 + 903 = 1806
Step 3: 1806 + 903 = 2709
Step 4: 2709 + 903 = 3612
Step 5: 3612 + 903 = 4515
Step 6: 4515 + 903 = 5418
Step 7: 5418 + 903 = 6321
Step 8: 6321 + 903 = 7224
Step 9: 7224 + 903 = 8127
Step 10: 8127 + 903 = 9030
Step 11: 9030 + 903 = 9933
Step 12: 9933 + 903 = 10836
Step 13: 10836 + 903 = 11739
Step 14: 11739 + 903 = 12642
Step 15: 12642 + 903 = 13545
Step 16: 13545 + 903 = 14448
Step 17: 14448 + 903 = 15351
Step 18: 15351 + 903 = 16254

So, 903*18 = 16254