Alright, let's solve this math problem step by step. First, we have the number 251. Next, we see the multiplication sign, which means we need to multiply something. And what are we multiplying it by? We multiply it by 87. So, we're going to take the number 251 and add it to itself 87 times.
Step 1: 0 + 251 = 251
Step 2: 251 + 251 = 502
Step 3: 502 + 251 = 753
Step 4: 753 + 251 = 1004
Step 5: 1004 + 251 = 1255
Step 6: 1255 + 251 = 1506
Step 7: 1506 + 251 = 1757
Step 8: 1757 + 251 = 2008
Step 9: 2008 + 251 = 2259
Step 10: 2259 + 251 = 2510
Step 11: 2510 + 251 = 2761
Step 12: 2761 + 251 = 3012
Step 13: 3012 + 251 = 3263
Step 14: 3263 + 251 = 3514
Step 15: 3514 + 251 = 3765
Step 16: 3765 + 251 = 4016
Step 17: 4016 + 251 = 4267
Step 18: 4267 + 251 = 4518
Step 19: 4518 + 251 = 4769
Step 20: 4769 + 251 = 5020
Step 21: 5020 + 251 = 5271
Step 22: 5271 + 251 = 5522
Step 23: 5522 + 251 = 5773
Step 24: 5773 + 251 = 6024
Step 25: 6024 + 251 = 6275
Step 26: 6275 + 251 = 6526
Step 27: 6526 + 251 = 6777
Step 28: 6777 + 251 = 7028
Step 29: 7028 + 251 = 7279
Step 30: 7279 + 251 = 7530
Step 31: 7530 + 251 = 7781
Step 32: 7781 + 251 = 8032
Step 33: 8032 + 251 = 8283
Step 34: 8283 + 251 = 8534
Step 35: 8534 + 251 = 8785
Step 36: 8785 + 251 = 9036
Step 37: 9036 + 251 = 9287
Step 38: 9287 + 251 = 9538
Step 39: 9538 + 251 = 9789
Step 40: 9789 + 251 = 10040
Step 41: 10040 + 251 = 10291
Step 42: 10291 + 251 = 10542
Step 43: 10542 + 251 = 10793
Step 44: 10793 + 251 = 11044
Step 45: 11044 + 251 = 11295
Step 46: 11295 + 251 = 11546
Step 47: 11546 + 251 = 11797
Step 48: 11797 + 251 = 12048
Step 49: 12048 + 251 = 12299
Step 50: 12299 + 251 = 12550
Step 51: 12550 + 251 = 12801
Step 52: 12801 + 251 = 13052
Step 53: 13052 + 251 = 13303
Step 54: 13303 + 251 = 13554
Step 55: 13554 + 251 = 13805
Step 56: 13805 + 251 = 14056
Step 57: 14056 + 251 = 14307
Step 58: 14307 + 251 = 14558
Step 59: 14558 + 251 = 14809
Step 60: 14809 + 251 = 15060
Step 61: 15060 + 251 = 15311
Step 62: 15311 + 251 = 15562
Step 63: 15562 + 251 = 15813
Step 64: 15813 + 251 = 16064
Step 65: 16064 + 251 = 16315
Step 66: 16315 + 251 = 16566
Step 67: 16566 + 251 = 16817
Step 68: 16817 + 251 = 17068
Step 69: 17068 + 251 = 17319
Step 70: 17319 + 251 = 17570
Step 71: 17570 + 251 = 17821
Step 72: 17821 + 251 = 18072
Step 73: 18072 + 251 = 18323
Step 74: 18323 + 251 = 18574
Step 75: 18574 + 251 = 18825
Step 76: 18825 + 251 = 19076
Step 77: 19076 + 251 = 19327
Step 78: 19327 + 251 = 19578
Step 79: 19578 + 251 = 19829
Step 80: 19829 + 251 = 20080
Step 81: 20080 + 251 = 20331
Step 82: 20331 + 251 = 20582
Step 83: 20582 + 251 = 20833
Step 84: 20833 + 251 = 21084
Step 85: 21084 + 251 = 21335
Step 86: 21335 + 251 = 21586
Step 87: 21586 + 251 = 21837

So, 251*87 = 21837