Sure thing! We've got 72 and we're gonna multiply it by 20. That's the same as adding 72 to itself 20 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
Step 14: 936 + 72 = 1008
Step 15: 1008 + 72 = 1080
Step 16: 1080 + 72 = 1152
Step 17: 1152 + 72 = 1224
Step 18: 1224 + 72 = 1296
Step 19: 1296 + 72 = 1368
Step 20: 1368 + 72 = 1440

So, 72*20 = 1440