Let's get this math done. We have 542 and we're going to multiply it by 39. This is the same as taking 542 and adding it to itself 39 times.
Step 1: 0 + 542 = 542
Step 2: 542 + 542 = 1084
Step 3: 1084 + 542 = 1626
Step 4: 1626 + 542 = 2168
Step 5: 2168 + 542 = 2710
Step 6: 2710 + 542 = 3252
Step 7: 3252 + 542 = 3794
Step 8: 3794 + 542 = 4336
Step 9: 4336 + 542 = 4878
Step 10: 4878 + 542 = 5420
Step 11: 5420 + 542 = 5962
Step 12: 5962 + 542 = 6504
Step 13: 6504 + 542 = 7046
Step 14: 7046 + 542 = 7588
Step 15: 7588 + 542 = 8130
Step 16: 8130 + 542 = 8672
Step 17: 8672 + 542 = 9214
Step 18: 9214 + 542 = 9756
Step 19: 9756 + 542 = 10298
Step 20: 10298 + 542 = 10840
Step 21: 10840 + 542 = 11382
Step 22: 11382 + 542 = 11924
Step 23: 11924 + 542 = 12466
Step 24: 12466 + 542 = 13008
Step 25: 13008 + 542 = 13550
Step 26: 13550 + 542 = 14092
Step 27: 14092 + 542 = 14634
Step 28: 14634 + 542 = 15176
Step 29: 15176 + 542 = 15718
Step 30: 15718 + 542 = 16260
Step 31: 16260 + 542 = 16802
Step 32: 16802 + 542 = 17344
Step 33: 17344 + 542 = 17886
Step 34: 17886 + 542 = 18428
Step 35: 18428 + 542 = 18970
Step 36: 18970 + 542 = 19512
Step 37: 19512 + 542 = 20054
Step 38: 20054 + 542 = 20596
Step 39: 20596 + 542 = 21138

So, 542*39 = 21138