Let's get this math done. We have 871 and we're going to multiply it by 51. This is the same as taking 871 and adding it to itself 51 times.
Step 1: 0 + 871 = 871
Step 2: 871 + 871 = 1742
Step 3: 1742 + 871 = 2613
Step 4: 2613 + 871 = 3484
Step 5: 3484 + 871 = 4355
Step 6: 4355 + 871 = 5226
Step 7: 5226 + 871 = 6097
Step 8: 6097 + 871 = 6968
Step 9: 6968 + 871 = 7839
Step 10: 7839 + 871 = 8710
Step 11: 8710 + 871 = 9581
Step 12: 9581 + 871 = 10452
Step 13: 10452 + 871 = 11323
Step 14: 11323 + 871 = 12194
Step 15: 12194 + 871 = 13065
Step 16: 13065 + 871 = 13936
Step 17: 13936 + 871 = 14807
Step 18: 14807 + 871 = 15678
Step 19: 15678 + 871 = 16549
Step 20: 16549 + 871 = 17420
Step 21: 17420 + 871 = 18291
Step 22: 18291 + 871 = 19162
Step 23: 19162 + 871 = 20033
Step 24: 20033 + 871 = 20904
Step 25: 20904 + 871 = 21775
Step 26: 21775 + 871 = 22646
Step 27: 22646 + 871 = 23517
Step 28: 23517 + 871 = 24388
Step 29: 24388 + 871 = 25259
Step 30: 25259 + 871 = 26130
Step 31: 26130 + 871 = 27001
Step 32: 27001 + 871 = 27872
Step 33: 27872 + 871 = 28743
Step 34: 28743 + 871 = 29614
Step 35: 29614 + 871 = 30485
Step 36: 30485 + 871 = 31356
Step 37: 31356 + 871 = 32227
Step 38: 32227 + 871 = 33098
Step 39: 33098 + 871 = 33969
Step 40: 33969 + 871 = 34840
Step 41: 34840 + 871 = 35711
Step 42: 35711 + 871 = 36582
Step 43: 36582 + 871 = 37453
Step 44: 37453 + 871 = 38324
Step 45: 38324 + 871 = 39195
Step 46: 39195 + 871 = 40066
Step 47: 40066 + 871 = 40937
Step 48: 40937 + 871 = 41808
Step 49: 41808 + 871 = 42679
Step 50: 42679 + 871 = 43550
Step 51: 43550 + 871 = 44421

So, 871*51 = 44421