OK, let's work through this together. We're starting with 131 and we're going to multiply it by 100, which means we add 131 to itself 100 times.
Step 1: 0 + 131 = 131
Step 2: 131 + 131 = 262
Step 3: 262 + 131 = 393
Step 4: 393 + 131 = 524
Step 5: 524 + 131 = 655
Step 6: 655 + 131 = 786
Step 7: 786 + 131 = 917
Step 8: 917 + 131 = 1048
Step 9: 1048 + 131 = 1179
Step 10: 1179 + 131 = 1310
Step 11: 1310 + 131 = 1441
Step 12: 1441 + 131 = 1572
Step 13: 1572 + 131 = 1703
Step 14: 1703 + 131 = 1834
Step 15: 1834 + 131 = 1965
Step 16: 1965 + 131 = 2096
Step 17: 2096 + 131 = 2227
Step 18: 2227 + 131 = 2358
Step 19: 2358 + 131 = 2489
Step 20: 2489 + 131 = 2620
Step 21: 2620 + 131 = 2751
Step 22: 2751 + 131 = 2882
Step 23: 2882 + 131 = 3013
Step 24: 3013 + 131 = 3144
Step 25: 3144 + 131 = 3275
Step 26: 3275 + 131 = 3406
Step 27: 3406 + 131 = 3537
Step 28: 3537 + 131 = 3668
Step 29: 3668 + 131 = 3799
Step 30: 3799 + 131 = 3930
Step 31: 3930 + 131 = 4061
Step 32: 4061 + 131 = 4192
Step 33: 4192 + 131 = 4323
Step 34: 4323 + 131 = 4454
Step 35: 4454 + 131 = 4585
Step 36: 4585 + 131 = 4716
Step 37: 4716 + 131 = 4847
Step 38: 4847 + 131 = 4978
Step 39: 4978 + 131 = 5109
Step 40: 5109 + 131 = 5240
Step 41: 5240 + 131 = 5371
Step 42: 5371 + 131 = 5502
Step 43: 5502 + 131 = 5633
Step 44: 5633 + 131 = 5764
Step 45: 5764 + 131 = 5895
Step 46: 5895 + 131 = 6026
Step 47: 6026 + 131 = 6157
Step 48: 6157 + 131 = 6288
Step 49: 6288 + 131 = 6419
Step 50: 6419 + 131 = 6550
Step 51: 6550 + 131 = 6681
Step 52: 6681 + 131 = 6812
Step 53: 6812 + 131 = 6943
Step 54: 6943 + 131 = 7074
Step 55: 7074 + 131 = 7205
Step 56: 7205 + 131 = 7336
Step 57: 7336 + 131 = 7467
Step 58: 7467 + 131 = 7598
Step 59: 7598 + 131 = 7729
Step 60: 7729 + 131 = 7860
Step 61: 7860 + 131 = 7991
Step 62: 7991 + 131 = 8122
Step 63: 8122 + 131 = 8253
Step 64: 8253 + 131 = 8384
Step 65: 8384 + 131 = 8515
Step 66: 8515 + 131 = 8646
Step 67: 8646 + 131 = 8777
Step 68: 8777 + 131 = 8908
Step 69: 8908 + 131 = 9039
Step 70: 9039 + 131 = 9170
Step 71: 9170 + 131 = 9301
Step 72: 9301 + 131 = 9432
Step 73: 9432 + 131 = 9563
Step 74: 9563 + 131 = 9694
Step 75: 9694 + 131 = 9825
Step 76: 9825 + 131 = 9956
Step 77: 9956 + 131 = 10087
Step 78: 10087 + 131 = 10218
Step 79: 10218 + 131 = 10349
Step 80: 10349 + 131 = 10480
Step 81: 10480 + 131 = 10611
Step 82: 10611 + 131 = 10742
Step 83: 10742 + 131 = 10873
Step 84: 10873 + 131 = 11004
Step 85: 11004 + 131 = 11135
Step 86: 11135 + 131 = 11266
Step 87: 11266 + 131 = 11397
Step 88: 11397 + 131 = 11528
Step 89: 11528 + 131 = 11659
Step 90: 11659 + 131 = 11790
Step 91: 11790 + 131 = 11921
Step 92: 11921 + 131 = 12052
Step 93: 12052 + 131 = 12183
Step 94: 12183 + 131 = 12314
Step 95: 12314 + 131 = 12445
Step 96: 12445 + 131 = 12576
Step 97: 12576 + 131 = 12707
Step 98: 12707 + 131 = 12838
Step 99: 12838 + 131 = 12969
Step 100: 12969 + 131 = 13100

So, 131*100 = 13100