Let's roll up our sleeves and solve this. We have 100 and we're going to multiply it by 257, essentially adding 100 to itself 257 times.
Step 1: 0 + 100 = 100
Step 2: 100 + 100 = 200
Step 3: 200 + 100 = 300
Step 4: 300 + 100 = 400
Step 5: 400 + 100 = 500
Step 6: 500 + 100 = 600
Step 7: 600 + 100 = 700
Step 8: 700 + 100 = 800
Step 9: 800 + 100 = 900
Step 10: 900 + 100 = 1000
Step 11: 1000 + 100 = 1100
Step 12: 1100 + 100 = 1200
Step 13: 1200 + 100 = 1300
Step 14: 1300 + 100 = 1400
Step 15: 1400 + 100 = 1500
Step 16: 1500 + 100 = 1600
Step 17: 1600 + 100 = 1700
Step 18: 1700 + 100 = 1800
Step 19: 1800 + 100 = 1900
Step 20: 1900 + 100 = 2000
Step 21: 2000 + 100 = 2100
Step 22: 2100 + 100 = 2200
Step 23: 2200 + 100 = 2300
Step 24: 2300 + 100 = 2400
Step 25: 2400 + 100 = 2500
Step 26: 2500 + 100 = 2600
Step 27: 2600 + 100 = 2700
Step 28: 2700 + 100 = 2800
Step 29: 2800 + 100 = 2900
Step 30: 2900 + 100 = 3000
Step 31: 3000 + 100 = 3100
Step 32: 3100 + 100 = 3200
Step 33: 3200 + 100 = 3300
Step 34: 3300 + 100 = 3400
Step 35: 3400 + 100 = 3500
Step 36: 3500 + 100 = 3600
Step 37: 3600 + 100 = 3700
Step 38: 3700 + 100 = 3800
Step 39: 3800 + 100 = 3900
Step 40: 3900 + 100 = 4000
Step 41: 4000 + 100 = 4100
Step 42: 4100 + 100 = 4200
Step 43: 4200 + 100 = 4300
Step 44: 4300 + 100 = 4400
Step 45: 4400 + 100 = 4500
Step 46: 4500 + 100 = 4600
Step 47: 4600 + 100 = 4700
Step 48: 4700 + 100 = 4800
Step 49: 4800 + 100 = 4900
Step 50: 4900 + 100 = 5000
Step 51: 5000 + 100 = 5100
Step 52: 5100 + 100 = 5200
Step 53: 5200 + 100 = 5300
Step 54: 5300 + 100 = 5400
Step 55: 5400 + 100 = 5500
Step 56: 5500 + 100 = 5600
Step 57: 5600 + 100 = 5700
Step 58: 5700 + 100 = 5800
Step 59: 5800 + 100 = 5900
Step 60: 5900 + 100 = 6000
Step 61: 6000 + 100 = 6100
Step 62: 6100 + 100 = 6200
Step 63: 6200 + 100 = 6300
Step 64: 6300 + 100 = 6400
Step 65: 6400 + 100 = 6500
Step 66: 6500 + 100 = 6600
Step 67: 6600 + 100 = 6700
Step 68: 6700 + 100 = 6800
Step 69: 6800 + 100 = 6900
Step 70: 6900 + 100 = 7000
Step 71: 7000 + 100 = 7100
Step 72: 7100 + 100 = 7200
Step 73: 7200 + 100 = 7300
Step 74: 7300 + 100 = 7400
Step 75: 7400 + 100 = 7500
Step 76: 7500 + 100 = 7600
Step 77: 7600 + 100 = 7700
Step 78: 7700 + 100 = 7800
Step 79: 7800 + 100 = 7900
Step 80: 7900 + 100 = 8000
Step 81: 8000 + 100 = 8100
Step 82: 8100 + 100 = 8200
Step 83: 8200 + 100 = 8300
Step 84: 8300 + 100 = 8400
Step 85: 8400 + 100 = 8500
Step 86: 8500 + 100 = 8600
Step 87: 8600 + 100 = 8700
Step 88: 8700 + 100 = 8800
Step 89: 8800 + 100 = 8900
Step 90: 8900 + 100 = 9000
Step 91: 9000 + 100 = 9100
Step 92: 9100 + 100 = 9200
Step 93: 9200 + 100 = 9300
Step 94: 9300 + 100 = 9400
Step 95: 9400 + 100 = 9500
Step 96: 9500 + 100 = 9600
Step 97: 9600 + 100 = 9700
Step 98: 9700 + 100 = 9800
Step 99: 9800 + 100 = 9900
Step 100: 9900 + 100 = 10000
Step 101: 10000 + 100 = 10100
Step 102: 10100 + 100 = 10200
Step 103: 10200 + 100 = 10300
Step 104: 10300 + 100 = 10400
Step 105: 10400 + 100 = 10500
Step 106: 10500 + 100 = 10600
Step 107: 10600 + 100 = 10700
Step 108: 10700 + 100 = 10800
Step 109: 10800 + 100 = 10900
Step 110: 10900 + 100 = 11000
Step 111: 11000 + 100 = 11100
Step 112: 11100 + 100 = 11200
Step 113: 11200 + 100 = 11300
Step 114: 11300 + 100 = 11400
Step 115: 11400 + 100 = 11500
Step 116: 11500 + 100 = 11600
Step 117: 11600 + 100 = 11700
Step 118: 11700 + 100 = 11800
Step 119: 11800 + 100 = 11900
Step 120: 11900 + 100 = 12000
Step 121: 12000 + 100 = 12100
Step 122: 12100 + 100 = 12200
Step 123: 12200 + 100 = 12300
Step 124: 12300 + 100 = 12400
Step 125: 12400 + 100 = 12500
Step 126: 12500 + 100 = 12600
Step 127: 12600 + 100 = 12700
Step 128: 12700 + 100 = 12800
Step 129: 12800 + 100 = 12900
Step 130: 12900 + 100 = 13000
Step 131: 13000 + 100 = 13100
Step 132: 13100 + 100 = 13200
Step 133: 13200 + 100 = 13300
Step 134: 13300 + 100 = 13400
Step 135: 13400 + 100 = 13500
Step 136: 13500 + 100 = 13600
Step 137: 13600 + 100 = 13700
Step 138: 13700 + 100 = 13800
Step 139: 13800 + 100 = 13900
Step 140: 13900 + 100 = 14000
Step 141: 14000 + 100 = 14100
Step 142: 14100 + 100 = 14200
Step 143: 14200 + 100 = 14300
Step 144: 14300 + 100 = 14400
Step 145: 14400 + 100 = 14500
Step 146: 14500 + 100 = 14600
Step 147: 14600 + 100 = 14700
Step 148: 14700 + 100 = 14800
Step 149: 14800 + 100 = 14900
Step 150: 14900 + 100 = 15000
Step 151: 15000 + 100 = 15100
Step 152: 15100 + 100 = 15200
Step 153: 15200 + 100 = 15300
Step 154: 15300 + 100 = 15400
Step 155: 15400 + 100 = 15500
Step 156: 15500 + 100 = 15600
Step 157: 15600 + 100 = 15700
Step 158: 15700 + 100 = 15800
Step 159: 15800 + 100 = 15900
Step 160: 15900 + 100 = 16000
Step 161: 16000 + 100 = 16100
Step 162: 16100 + 100 = 16200
Step 163: 16200 + 100 = 16300
Step 164: 16300 + 100 = 16400
Step 165: 16400 + 100 = 16500
Step 166: 16500 + 100 = 16600
Step 167: 16600 + 100 = 16700
Step 168: 16700 + 100 = 16800
Step 169: 16800 + 100 = 16900
Step 170: 16900 + 100 = 17000
Step 171: 17000 + 100 = 17100
Step 172: 17100 + 100 = 17200
Step 173: 17200 + 100 = 17300
Step 174: 17300 + 100 = 17400
Step 175: 17400 + 100 = 17500
Step 176: 17500 + 100 = 17600
Step 177: 17600 + 100 = 17700
Step 178: 17700 + 100 = 17800
Step 179: 17800 + 100 = 17900
Step 180: 17900 + 100 = 18000
Step 181: 18000 + 100 = 18100
Step 182: 18100 + 100 = 18200
Step 183: 18200 + 100 = 18300
Step 184: 18300 + 100 = 18400
Step 185: 18400 + 100 = 18500
Step 186: 18500 + 100 = 18600
Step 187: 18600 + 100 = 18700
Step 188: 18700 + 100 = 18800
Step 189: 18800 + 100 = 18900
Step 190: 18900 + 100 = 19000
Step 191: 19000 + 100 = 19100
Step 192: 19100 + 100 = 19200
Step 193: 19200 + 100 = 19300
Step 194: 19300 + 100 = 19400
Step 195: 19400 + 100 = 19500
Step 196: 19500 + 100 = 19600
Step 197: 19600 + 100 = 19700
Step 198: 19700 + 100 = 19800
Step 199: 19800 + 100 = 19900
Step 200: 19900 + 100 = 20000
Step 201: 20000 + 100 = 20100
Step 202: 20100 + 100 = 20200
Step 203: 20200 + 100 = 20300
Step 204: 20300 + 100 = 20400
Step 205: 20400 + 100 = 20500
Step 206: 20500 + 100 = 20600
Step 207: 20600 + 100 = 20700
Step 208: 20700 + 100 = 20800
Step 209: 20800 + 100 = 20900
Step 210: 20900 + 100 = 21000
Step 211: 21000 + 100 = 21100
Step 212: 21100 + 100 = 21200
Step 213: 21200 + 100 = 21300
Step 214: 21300 + 100 = 21400
Step 215: 21400 + 100 = 21500
Step 216: 21500 + 100 = 21600
Step 217: 21600 + 100 = 21700
Step 218: 21700 + 100 = 21800
Step 219: 21800 + 100 = 21900
Step 220: 21900 + 100 = 22000
Step 221: 22000 + 100 = 22100
Step 222: 22100 + 100 = 22200
Step 223: 22200 + 100 = 22300
Step 224: 22300 + 100 = 22400
Step 225: 22400 + 100 = 22500
Step 226: 22500 + 100 = 22600
Step 227: 22600 + 100 = 22700
Step 228: 22700 + 100 = 22800
Step 229: 22800 + 100 = 22900
Step 230: 22900 + 100 = 23000
Step 231: 23000 + 100 = 23100
Step 232: 23100 + 100 = 23200
Step 233: 23200 + 100 = 23300
Step 234: 23300 + 100 = 23400
Step 235: 23400 + 100 = 23500
Step 236: 23500 + 100 = 23600
Step 237: 23600 + 100 = 23700
Step 238: 23700 + 100 = 23800
Step 239: 23800 + 100 = 23900
Step 240: 23900 + 100 = 24000
Step 241: 24000 + 100 = 24100
Step 242: 24100 + 100 = 24200
Step 243: 24200 + 100 = 24300
Step 244: 24300 + 100 = 24400
Step 245: 24400 + 100 = 24500
Step 246: 24500 + 100 = 24600
Step 247: 24600 + 100 = 24700
Step 248: 24700 + 100 = 24800
Step 249: 24800 + 100 = 24900
Step 250: 24900 + 100 = 25000
Step 251: 25000 + 100 = 25100
Step 252: 25100 + 100 = 25200
Step 253: 25200 + 100 = 25300
Step 254: 25300 + 100 = 25400
Step 255: 25400 + 100 = 25500
Step 256: 25500 + 100 = 25600
Step 257: 25600 + 100 = 25700

So, 100*257 = 25700