Let's roll up our sleeves and solve this. We have 87 and we're going to multiply it by 87, essentially adding 87 to itself 87 times.
Step 1: 0 + 87 = 87
Step 2: 87 + 87 = 174
Step 3: 174 + 87 = 261
Step 4: 261 + 87 = 348
Step 5: 348 + 87 = 435
Step 6: 435 + 87 = 522
Step 7: 522 + 87 = 609
Step 8: 609 + 87 = 696
Step 9: 696 + 87 = 783
Step 10: 783 + 87 = 870
Step 11: 870 + 87 = 957
Step 12: 957 + 87 = 1044
Step 13: 1044 + 87 = 1131
Step 14: 1131 + 87 = 1218
Step 15: 1218 + 87 = 1305
Step 16: 1305 + 87 = 1392
Step 17: 1392 + 87 = 1479
Step 18: 1479 + 87 = 1566
Step 19: 1566 + 87 = 1653
Step 20: 1653 + 87 = 1740
Step 21: 1740 + 87 = 1827
Step 22: 1827 + 87 = 1914
Step 23: 1914 + 87 = 2001
Step 24: 2001 + 87 = 2088
Step 25: 2088 + 87 = 2175
Step 26: 2175 + 87 = 2262
Step 27: 2262 + 87 = 2349
Step 28: 2349 + 87 = 2436
Step 29: 2436 + 87 = 2523
Step 30: 2523 + 87 = 2610
Step 31: 2610 + 87 = 2697
Step 32: 2697 + 87 = 2784
Step 33: 2784 + 87 = 2871
Step 34: 2871 + 87 = 2958
Step 35: 2958 + 87 = 3045
Step 36: 3045 + 87 = 3132
Step 37: 3132 + 87 = 3219
Step 38: 3219 + 87 = 3306
Step 39: 3306 + 87 = 3393
Step 40: 3393 + 87 = 3480
Step 41: 3480 + 87 = 3567
Step 42: 3567 + 87 = 3654
Step 43: 3654 + 87 = 3741
Step 44: 3741 + 87 = 3828
Step 45: 3828 + 87 = 3915
Step 46: 3915 + 87 = 4002
Step 47: 4002 + 87 = 4089
Step 48: 4089 + 87 = 4176
Step 49: 4176 + 87 = 4263
Step 50: 4263 + 87 = 4350
Step 51: 4350 + 87 = 4437
Step 52: 4437 + 87 = 4524
Step 53: 4524 + 87 = 4611
Step 54: 4611 + 87 = 4698
Step 55: 4698 + 87 = 4785
Step 56: 4785 + 87 = 4872
Step 57: 4872 + 87 = 4959
Step 58: 4959 + 87 = 5046
Step 59: 5046 + 87 = 5133
Step 60: 5133 + 87 = 5220
Step 61: 5220 + 87 = 5307
Step 62: 5307 + 87 = 5394
Step 63: 5394 + 87 = 5481
Step 64: 5481 + 87 = 5568
Step 65: 5568 + 87 = 5655
Step 66: 5655 + 87 = 5742
Step 67: 5742 + 87 = 5829
Step 68: 5829 + 87 = 5916
Step 69: 5916 + 87 = 6003
Step 70: 6003 + 87 = 6090
Step 71: 6090 + 87 = 6177
Step 72: 6177 + 87 = 6264
Step 73: 6264 + 87 = 6351
Step 74: 6351 + 87 = 6438
Step 75: 6438 + 87 = 6525
Step 76: 6525 + 87 = 6612
Step 77: 6612 + 87 = 6699
Step 78: 6699 + 87 = 6786
Step 79: 6786 + 87 = 6873
Step 80: 6873 + 87 = 6960
Step 81: 6960 + 87 = 7047
Step 82: 7047 + 87 = 7134
Step 83: 7134 + 87 = 7221
Step 84: 7221 + 87 = 7308
Step 85: 7308 + 87 = 7395
Step 86: 7395 + 87 = 7482
Step 87: 7482 + 87 = 7569

So, 87*87 = 7569