Let's roll up our sleeves and solve this. We have 843 and we're going to multiply it by 61, essentially adding 843 to itself 61 times.
Step 1: 0 + 843 = 843
Step 2: 843 + 843 = 1686
Step 3: 1686 + 843 = 2529
Step 4: 2529 + 843 = 3372
Step 5: 3372 + 843 = 4215
Step 6: 4215 + 843 = 5058
Step 7: 5058 + 843 = 5901
Step 8: 5901 + 843 = 6744
Step 9: 6744 + 843 = 7587
Step 10: 7587 + 843 = 8430
Step 11: 8430 + 843 = 9273
Step 12: 9273 + 843 = 10116
Step 13: 10116 + 843 = 10959
Step 14: 10959 + 843 = 11802
Step 15: 11802 + 843 = 12645
Step 16: 12645 + 843 = 13488
Step 17: 13488 + 843 = 14331
Step 18: 14331 + 843 = 15174
Step 19: 15174 + 843 = 16017
Step 20: 16017 + 843 = 16860
Step 21: 16860 + 843 = 17703
Step 22: 17703 + 843 = 18546
Step 23: 18546 + 843 = 19389
Step 24: 19389 + 843 = 20232
Step 25: 20232 + 843 = 21075
Step 26: 21075 + 843 = 21918
Step 27: 21918 + 843 = 22761
Step 28: 22761 + 843 = 23604
Step 29: 23604 + 843 = 24447
Step 30: 24447 + 843 = 25290
Step 31: 25290 + 843 = 26133
Step 32: 26133 + 843 = 26976
Step 33: 26976 + 843 = 27819
Step 34: 27819 + 843 = 28662
Step 35: 28662 + 843 = 29505
Step 36: 29505 + 843 = 30348
Step 37: 30348 + 843 = 31191
Step 38: 31191 + 843 = 32034
Step 39: 32034 + 843 = 32877
Step 40: 32877 + 843 = 33720
Step 41: 33720 + 843 = 34563
Step 42: 34563 + 843 = 35406
Step 43: 35406 + 843 = 36249
Step 44: 36249 + 843 = 37092
Step 45: 37092 + 843 = 37935
Step 46: 37935 + 843 = 38778
Step 47: 38778 + 843 = 39621
Step 48: 39621 + 843 = 40464
Step 49: 40464 + 843 = 41307
Step 50: 41307 + 843 = 42150
Step 51: 42150 + 843 = 42993
Step 52: 42993 + 843 = 43836
Step 53: 43836 + 843 = 44679
Step 54: 44679 + 843 = 45522
Step 55: 45522 + 843 = 46365
Step 56: 46365 + 843 = 47208
Step 57: 47208 + 843 = 48051
Step 58: 48051 + 843 = 48894
Step 59: 48894 + 843 = 49737
Step 60: 49737 + 843 = 50580
Step 61: 50580 + 843 = 51423

So, 843*61 = 51423