Let's get this math done. We have 257 and we're going to multiply it by 20. This is the same as taking 257 and adding it to itself 20 times.
Step 1: 0 + 257 = 257
Step 2: 257 + 257 = 514
Step 3: 514 + 257 = 771
Step 4: 771 + 257 = 1028
Step 5: 1028 + 257 = 1285
Step 6: 1285 + 257 = 1542
Step 7: 1542 + 257 = 1799
Step 8: 1799 + 257 = 2056
Step 9: 2056 + 257 = 2313
Step 10: 2313 + 257 = 2570
Step 11: 2570 + 257 = 2827
Step 12: 2827 + 257 = 3084
Step 13: 3084 + 257 = 3341
Step 14: 3341 + 257 = 3598
Step 15: 3598 + 257 = 3855
Step 16: 3855 + 257 = 4112
Step 17: 4112 + 257 = 4369
Step 18: 4369 + 257 = 4626
Step 19: 4626 + 257 = 4883
Step 20: 4883 + 257 = 5140

So, 257*20 = 5140