Let's get this math done. We have 520 and we're going to multiply it by 155. This is the same as taking 520 and adding it to itself 155 times.
Step 1: 0 + 520 = 520
Step 2: 520 + 520 = 1040
Step 3: 1040 + 520 = 1560
Step 4: 1560 + 520 = 2080
Step 5: 2080 + 520 = 2600
Step 6: 2600 + 520 = 3120
Step 7: 3120 + 520 = 3640
Step 8: 3640 + 520 = 4160
Step 9: 4160 + 520 = 4680
Step 10: 4680 + 520 = 5200
Step 11: 5200 + 520 = 5720
Step 12: 5720 + 520 = 6240
Step 13: 6240 + 520 = 6760
Step 14: 6760 + 520 = 7280
Step 15: 7280 + 520 = 7800
Step 16: 7800 + 520 = 8320
Step 17: 8320 + 520 = 8840
Step 18: 8840 + 520 = 9360
Step 19: 9360 + 520 = 9880
Step 20: 9880 + 520 = 10400
Step 21: 10400 + 520 = 10920
Step 22: 10920 + 520 = 11440
Step 23: 11440 + 520 = 11960
Step 24: 11960 + 520 = 12480
Step 25: 12480 + 520 = 13000
Step 26: 13000 + 520 = 13520
Step 27: 13520 + 520 = 14040
Step 28: 14040 + 520 = 14560
Step 29: 14560 + 520 = 15080
Step 30: 15080 + 520 = 15600
Step 31: 15600 + 520 = 16120
Step 32: 16120 + 520 = 16640
Step 33: 16640 + 520 = 17160
Step 34: 17160 + 520 = 17680
Step 35: 17680 + 520 = 18200
Step 36: 18200 + 520 = 18720
Step 37: 18720 + 520 = 19240
Step 38: 19240 + 520 = 19760
Step 39: 19760 + 520 = 20280
Step 40: 20280 + 520 = 20800
Step 41: 20800 + 520 = 21320
Step 42: 21320 + 520 = 21840
Step 43: 21840 + 520 = 22360
Step 44: 22360 + 520 = 22880
Step 45: 22880 + 520 = 23400
Step 46: 23400 + 520 = 23920
Step 47: 23920 + 520 = 24440
Step 48: 24440 + 520 = 24960
Step 49: 24960 + 520 = 25480
Step 50: 25480 + 520 = 26000
Step 51: 26000 + 520 = 26520
Step 52: 26520 + 520 = 27040
Step 53: 27040 + 520 = 27560
Step 54: 27560 + 520 = 28080
Step 55: 28080 + 520 = 28600
Step 56: 28600 + 520 = 29120
Step 57: 29120 + 520 = 29640
Step 58: 29640 + 520 = 30160
Step 59: 30160 + 520 = 30680
Step 60: 30680 + 520 = 31200
Step 61: 31200 + 520 = 31720
Step 62: 31720 + 520 = 32240
Step 63: 32240 + 520 = 32760
Step 64: 32760 + 520 = 33280
Step 65: 33280 + 520 = 33800
Step 66: 33800 + 520 = 34320
Step 67: 34320 + 520 = 34840
Step 68: 34840 + 520 = 35360
Step 69: 35360 + 520 = 35880
Step 70: 35880 + 520 = 36400
Step 71: 36400 + 520 = 36920
Step 72: 36920 + 520 = 37440
Step 73: 37440 + 520 = 37960
Step 74: 37960 + 520 = 38480
Step 75: 38480 + 520 = 39000
Step 76: 39000 + 520 = 39520
Step 77: 39520 + 520 = 40040
Step 78: 40040 + 520 = 40560
Step 79: 40560 + 520 = 41080
Step 80: 41080 + 520 = 41600
Step 81: 41600 + 520 = 42120
Step 82: 42120 + 520 = 42640
Step 83: 42640 + 520 = 43160
Step 84: 43160 + 520 = 43680
Step 85: 43680 + 520 = 44200
Step 86: 44200 + 520 = 44720
Step 87: 44720 + 520 = 45240
Step 88: 45240 + 520 = 45760
Step 89: 45760 + 520 = 46280
Step 90: 46280 + 520 = 46800
Step 91: 46800 + 520 = 47320
Step 92: 47320 + 520 = 47840
Step 93: 47840 + 520 = 48360
Step 94: 48360 + 520 = 48880
Step 95: 48880 + 520 = 49400
Step 96: 49400 + 520 = 49920
Step 97: 49920 + 520 = 50440
Step 98: 50440 + 520 = 50960
Step 99: 50960 + 520 = 51480
Step 100: 51480 + 520 = 52000
Step 101: 52000 + 520 = 52520
Step 102: 52520 + 520 = 53040
Step 103: 53040 + 520 = 53560
Step 104: 53560 + 520 = 54080
Step 105: 54080 + 520 = 54600
Step 106: 54600 + 520 = 55120
Step 107: 55120 + 520 = 55640
Step 108: 55640 + 520 = 56160
Step 109: 56160 + 520 = 56680
Step 110: 56680 + 520 = 57200
Step 111: 57200 + 520 = 57720
Step 112: 57720 + 520 = 58240
Step 113: 58240 + 520 = 58760
Step 114: 58760 + 520 = 59280
Step 115: 59280 + 520 = 59800
Step 116: 59800 + 520 = 60320
Step 117: 60320 + 520 = 60840
Step 118: 60840 + 520 = 61360
Step 119: 61360 + 520 = 61880
Step 120: 61880 + 520 = 62400
Step 121: 62400 + 520 = 62920
Step 122: 62920 + 520 = 63440
Step 123: 63440 + 520 = 63960
Step 124: 63960 + 520 = 64480
Step 125: 64480 + 520 = 65000
Step 126: 65000 + 520 = 65520
Step 127: 65520 + 520 = 66040
Step 128: 66040 + 520 = 66560
Step 129: 66560 + 520 = 67080
Step 130: 67080 + 520 = 67600
Step 131: 67600 + 520 = 68120
Step 132: 68120 + 520 = 68640
Step 133: 68640 + 520 = 69160
Step 134: 69160 + 520 = 69680
Step 135: 69680 + 520 = 70200
Step 136: 70200 + 520 = 70720
Step 137: 70720 + 520 = 71240
Step 138: 71240 + 520 = 71760
Step 139: 71760 + 520 = 72280
Step 140: 72280 + 520 = 72800
Step 141: 72800 + 520 = 73320
Step 142: 73320 + 520 = 73840
Step 143: 73840 + 520 = 74360
Step 144: 74360 + 520 = 74880
Step 145: 74880 + 520 = 75400
Step 146: 75400 + 520 = 75920
Step 147: 75920 + 520 = 76440
Step 148: 76440 + 520 = 76960
Step 149: 76960 + 520 = 77480
Step 150: 77480 + 520 = 78000
Step 151: 78000 + 520 = 78520
Step 152: 78520 + 520 = 79040
Step 153: 79040 + 520 = 79560
Step 154: 79560 + 520 = 80080
Step 155: 80080 + 520 = 80600

So, 520*155 = 80600