Let's roll up our sleeves and solve this. We have 72 and we're going to multiply it by 13, essentially adding 72 to itself 13 times.
Step 1: 0 + 72 = 72
Step 2: 72 + 72 = 144
Step 3: 144 + 72 = 216
Step 4: 216 + 72 = 288
Step 5: 288 + 72 = 360
Step 6: 360 + 72 = 432
Step 7: 432 + 72 = 504
Step 8: 504 + 72 = 576
Step 9: 576 + 72 = 648
Step 10: 648 + 72 = 720
Step 11: 720 + 72 = 792
Step 12: 792 + 72 = 864
Step 13: 864 + 72 = 936

So, 72*13 = 936