Let's get this math done. We have 287 and we're going to multiply it by 100. This is the same as taking 287 and adding it to itself 100 times.
Step 1: 0 + 287 = 287
Step 2: 287 + 287 = 574
Step 3: 574 + 287 = 861
Step 4: 861 + 287 = 1148
Step 5: 1148 + 287 = 1435
Step 6: 1435 + 287 = 1722
Step 7: 1722 + 287 = 2009
Step 8: 2009 + 287 = 2296
Step 9: 2296 + 287 = 2583
Step 10: 2583 + 287 = 2870
Step 11: 2870 + 287 = 3157
Step 12: 3157 + 287 = 3444
Step 13: 3444 + 287 = 3731
Step 14: 3731 + 287 = 4018
Step 15: 4018 + 287 = 4305
Step 16: 4305 + 287 = 4592
Step 17: 4592 + 287 = 4879
Step 18: 4879 + 287 = 5166
Step 19: 5166 + 287 = 5453
Step 20: 5453 + 287 = 5740
Step 21: 5740 + 287 = 6027
Step 22: 6027 + 287 = 6314
Step 23: 6314 + 287 = 6601
Step 24: 6601 + 287 = 6888
Step 25: 6888 + 287 = 7175
Step 26: 7175 + 287 = 7462
Step 27: 7462 + 287 = 7749
Step 28: 7749 + 287 = 8036
Step 29: 8036 + 287 = 8323
Step 30: 8323 + 287 = 8610
Step 31: 8610 + 287 = 8897
Step 32: 8897 + 287 = 9184
Step 33: 9184 + 287 = 9471
Step 34: 9471 + 287 = 9758
Step 35: 9758 + 287 = 10045
Step 36: 10045 + 287 = 10332
Step 37: 10332 + 287 = 10619
Step 38: 10619 + 287 = 10906
Step 39: 10906 + 287 = 11193
Step 40: 11193 + 287 = 11480
Step 41: 11480 + 287 = 11767
Step 42: 11767 + 287 = 12054
Step 43: 12054 + 287 = 12341
Step 44: 12341 + 287 = 12628
Step 45: 12628 + 287 = 12915
Step 46: 12915 + 287 = 13202
Step 47: 13202 + 287 = 13489
Step 48: 13489 + 287 = 13776
Step 49: 13776 + 287 = 14063
Step 50: 14063 + 287 = 14350
Step 51: 14350 + 287 = 14637
Step 52: 14637 + 287 = 14924
Step 53: 14924 + 287 = 15211
Step 54: 15211 + 287 = 15498
Step 55: 15498 + 287 = 15785
Step 56: 15785 + 287 = 16072
Step 57: 16072 + 287 = 16359
Step 58: 16359 + 287 = 16646
Step 59: 16646 + 287 = 16933
Step 60: 16933 + 287 = 17220
Step 61: 17220 + 287 = 17507
Step 62: 17507 + 287 = 17794
Step 63: 17794 + 287 = 18081
Step 64: 18081 + 287 = 18368
Step 65: 18368 + 287 = 18655
Step 66: 18655 + 287 = 18942
Step 67: 18942 + 287 = 19229
Step 68: 19229 + 287 = 19516
Step 69: 19516 + 287 = 19803
Step 70: 19803 + 287 = 20090
Step 71: 20090 + 287 = 20377
Step 72: 20377 + 287 = 20664
Step 73: 20664 + 287 = 20951
Step 74: 20951 + 287 = 21238
Step 75: 21238 + 287 = 21525
Step 76: 21525 + 287 = 21812
Step 77: 21812 + 287 = 22099
Step 78: 22099 + 287 = 22386
Step 79: 22386 + 287 = 22673
Step 80: 22673 + 287 = 22960
Step 81: 22960 + 287 = 23247
Step 82: 23247 + 287 = 23534
Step 83: 23534 + 287 = 23821
Step 84: 23821 + 287 = 24108
Step 85: 24108 + 287 = 24395
Step 86: 24395 + 287 = 24682
Step 87: 24682 + 287 = 24969
Step 88: 24969 + 287 = 25256
Step 89: 25256 + 287 = 25543
Step 90: 25543 + 287 = 25830
Step 91: 25830 + 287 = 26117
Step 92: 26117 + 287 = 26404
Step 93: 26404 + 287 = 26691
Step 94: 26691 + 287 = 26978
Step 95: 26978 + 287 = 27265
Step 96: 27265 + 287 = 27552
Step 97: 27552 + 287 = 27839
Step 98: 27839 + 287 = 28126
Step 99: 28126 + 287 = 28413
Step 100: 28413 + 287 = 28700

So, 287*100 = 28700