OK, let's work through this together. We're starting with 280 and we're going to multiply it by 256, which means we add 280 to itself 256 times.
Step 1: 0 + 280 = 280
Step 2: 280 + 280 = 560
Step 3: 560 + 280 = 840
Step 4: 840 + 280 = 1120
Step 5: 1120 + 280 = 1400
Step 6: 1400 + 280 = 1680
Step 7: 1680 + 280 = 1960
Step 8: 1960 + 280 = 2240
Step 9: 2240 + 280 = 2520
Step 10: 2520 + 280 = 2800
Step 11: 2800 + 280 = 3080
Step 12: 3080 + 280 = 3360
Step 13: 3360 + 280 = 3640
Step 14: 3640 + 280 = 3920
Step 15: 3920 + 280 = 4200
Step 16: 4200 + 280 = 4480
Step 17: 4480 + 280 = 4760
Step 18: 4760 + 280 = 5040
Step 19: 5040 + 280 = 5320
Step 20: 5320 + 280 = 5600
Step 21: 5600 + 280 = 5880
Step 22: 5880 + 280 = 6160
Step 23: 6160 + 280 = 6440
Step 24: 6440 + 280 = 6720
Step 25: 6720 + 280 = 7000
Step 26: 7000 + 280 = 7280
Step 27: 7280 + 280 = 7560
Step 28: 7560 + 280 = 7840
Step 29: 7840 + 280 = 8120
Step 30: 8120 + 280 = 8400
Step 31: 8400 + 280 = 8680
Step 32: 8680 + 280 = 8960
Step 33: 8960 + 280 = 9240
Step 34: 9240 + 280 = 9520
Step 35: 9520 + 280 = 9800
Step 36: 9800 + 280 = 10080
Step 37: 10080 + 280 = 10360
Step 38: 10360 + 280 = 10640
Step 39: 10640 + 280 = 10920
Step 40: 10920 + 280 = 11200
Step 41: 11200 + 280 = 11480
Step 42: 11480 + 280 = 11760
Step 43: 11760 + 280 = 12040
Step 44: 12040 + 280 = 12320
Step 45: 12320 + 280 = 12600
Step 46: 12600 + 280 = 12880
Step 47: 12880 + 280 = 13160
Step 48: 13160 + 280 = 13440
Step 49: 13440 + 280 = 13720
Step 50: 13720 + 280 = 14000
Step 51: 14000 + 280 = 14280
Step 52: 14280 + 280 = 14560
Step 53: 14560 + 280 = 14840
Step 54: 14840 + 280 = 15120
Step 55: 15120 + 280 = 15400
Step 56: 15400 + 280 = 15680
Step 57: 15680 + 280 = 15960
Step 58: 15960 + 280 = 16240
Step 59: 16240 + 280 = 16520
Step 60: 16520 + 280 = 16800
Step 61: 16800 + 280 = 17080
Step 62: 17080 + 280 = 17360
Step 63: 17360 + 280 = 17640
Step 64: 17640 + 280 = 17920
Step 65: 17920 + 280 = 18200
Step 66: 18200 + 280 = 18480
Step 67: 18480 + 280 = 18760
Step 68: 18760 + 280 = 19040
Step 69: 19040 + 280 = 19320
Step 70: 19320 + 280 = 19600
Step 71: 19600 + 280 = 19880
Step 72: 19880 + 280 = 20160
Step 73: 20160 + 280 = 20440
Step 74: 20440 + 280 = 20720
Step 75: 20720 + 280 = 21000
Step 76: 21000 + 280 = 21280
Step 77: 21280 + 280 = 21560
Step 78: 21560 + 280 = 21840
Step 79: 21840 + 280 = 22120
Step 80: 22120 + 280 = 22400
Step 81: 22400 + 280 = 22680
Step 82: 22680 + 280 = 22960
Step 83: 22960 + 280 = 23240
Step 84: 23240 + 280 = 23520
Step 85: 23520 + 280 = 23800
Step 86: 23800 + 280 = 24080
Step 87: 24080 + 280 = 24360
Step 88: 24360 + 280 = 24640
Step 89: 24640 + 280 = 24920
Step 90: 24920 + 280 = 25200
Step 91: 25200 + 280 = 25480
Step 92: 25480 + 280 = 25760
Step 93: 25760 + 280 = 26040
Step 94: 26040 + 280 = 26320
Step 95: 26320 + 280 = 26600
Step 96: 26600 + 280 = 26880
Step 97: 26880 + 280 = 27160
Step 98: 27160 + 280 = 27440
Step 99: 27440 + 280 = 27720
Step 100: 27720 + 280 = 28000
Step 101: 28000 + 280 = 28280
Step 102: 28280 + 280 = 28560
Step 103: 28560 + 280 = 28840
Step 104: 28840 + 280 = 29120
Step 105: 29120 + 280 = 29400
Step 106: 29400 + 280 = 29680
Step 107: 29680 + 280 = 29960
Step 108: 29960 + 280 = 30240
Step 109: 30240 + 280 = 30520
Step 110: 30520 + 280 = 30800
Step 111: 30800 + 280 = 31080
Step 112: 31080 + 280 = 31360
Step 113: 31360 + 280 = 31640
Step 114: 31640 + 280 = 31920
Step 115: 31920 + 280 = 32200
Step 116: 32200 + 280 = 32480
Step 117: 32480 + 280 = 32760
Step 118: 32760 + 280 = 33040
Step 119: 33040 + 280 = 33320
Step 120: 33320 + 280 = 33600
Step 121: 33600 + 280 = 33880
Step 122: 33880 + 280 = 34160
Step 123: 34160 + 280 = 34440
Step 124: 34440 + 280 = 34720
Step 125: 34720 + 280 = 35000
Step 126: 35000 + 280 = 35280
Step 127: 35280 + 280 = 35560
Step 128: 35560 + 280 = 35840
Step 129: 35840 + 280 = 36120
Step 130: 36120 + 280 = 36400
Step 131: 36400 + 280 = 36680
Step 132: 36680 + 280 = 36960
Step 133: 36960 + 280 = 37240
Step 134: 37240 + 280 = 37520
Step 135: 37520 + 280 = 37800
Step 136: 37800 + 280 = 38080
Step 137: 38080 + 280 = 38360
Step 138: 38360 + 280 = 38640
Step 139: 38640 + 280 = 38920
Step 140: 38920 + 280 = 39200
Step 141: 39200 + 280 = 39480
Step 142: 39480 + 280 = 39760
Step 143: 39760 + 280 = 40040
Step 144: 40040 + 280 = 40320
Step 145: 40320 + 280 = 40600
Step 146: 40600 + 280 = 40880
Step 147: 40880 + 280 = 41160
Step 148: 41160 + 280 = 41440
Step 149: 41440 + 280 = 41720
Step 150: 41720 + 280 = 42000
Step 151: 42000 + 280 = 42280
Step 152: 42280 + 280 = 42560
Step 153: 42560 + 280 = 42840
Step 154: 42840 + 280 = 43120
Step 155: 43120 + 280 = 43400
Step 156: 43400 + 280 = 43680
Step 157: 43680 + 280 = 43960
Step 158: 43960 + 280 = 44240
Step 159: 44240 + 280 = 44520
Step 160: 44520 + 280 = 44800
Step 161: 44800 + 280 = 45080
Step 162: 45080 + 280 = 45360
Step 163: 45360 + 280 = 45640
Step 164: 45640 + 280 = 45920
Step 165: 45920 + 280 = 46200
Step 166: 46200 + 280 = 46480
Step 167: 46480 + 280 = 46760
Step 168: 46760 + 280 = 47040
Step 169: 47040 + 280 = 47320
Step 170: 47320 + 280 = 47600
Step 171: 47600 + 280 = 47880
Step 172: 47880 + 280 = 48160
Step 173: 48160 + 280 = 48440
Step 174: 48440 + 280 = 48720
Step 175: 48720 + 280 = 49000
Step 176: 49000 + 280 = 49280
Step 177: 49280 + 280 = 49560
Step 178: 49560 + 280 = 49840
Step 179: 49840 + 280 = 50120
Step 180: 50120 + 280 = 50400
Step 181: 50400 + 280 = 50680
Step 182: 50680 + 280 = 50960
Step 183: 50960 + 280 = 51240
Step 184: 51240 + 280 = 51520
Step 185: 51520 + 280 = 51800
Step 186: 51800 + 280 = 52080
Step 187: 52080 + 280 = 52360
Step 188: 52360 + 280 = 52640
Step 189: 52640 + 280 = 52920
Step 190: 52920 + 280 = 53200
Step 191: 53200 + 280 = 53480
Step 192: 53480 + 280 = 53760
Step 193: 53760 + 280 = 54040
Step 194: 54040 + 280 = 54320
Step 195: 54320 + 280 = 54600
Step 196: 54600 + 280 = 54880
Step 197: 54880 + 280 = 55160
Step 198: 55160 + 280 = 55440
Step 199: 55440 + 280 = 55720
Step 200: 55720 + 280 = 56000
Step 201: 56000 + 280 = 56280
Step 202: 56280 + 280 = 56560
Step 203: 56560 + 280 = 56840
Step 204: 56840 + 280 = 57120
Step 205: 57120 + 280 = 57400
Step 206: 57400 + 280 = 57680
Step 207: 57680 + 280 = 57960
Step 208: 57960 + 280 = 58240
Step 209: 58240 + 280 = 58520
Step 210: 58520 + 280 = 58800
Step 211: 58800 + 280 = 59080
Step 212: 59080 + 280 = 59360
Step 213: 59360 + 280 = 59640
Step 214: 59640 + 280 = 59920
Step 215: 59920 + 280 = 60200
Step 216: 60200 + 280 = 60480
Step 217: 60480 + 280 = 60760
Step 218: 60760 + 280 = 61040
Step 219: 61040 + 280 = 61320
Step 220: 61320 + 280 = 61600
Step 221: 61600 + 280 = 61880
Step 222: 61880 + 280 = 62160
Step 223: 62160 + 280 = 62440
Step 224: 62440 + 280 = 62720
Step 225: 62720 + 280 = 63000
Step 226: 63000 + 280 = 63280
Step 227: 63280 + 280 = 63560
Step 228: 63560 + 280 = 63840
Step 229: 63840 + 280 = 64120
Step 230: 64120 + 280 = 64400
Step 231: 64400 + 280 = 64680
Step 232: 64680 + 280 = 64960
Step 233: 64960 + 280 = 65240
Step 234: 65240 + 280 = 65520
Step 235: 65520 + 280 = 65800
Step 236: 65800 + 280 = 66080
Step 237: 66080 + 280 = 66360
Step 238: 66360 + 280 = 66640
Step 239: 66640 + 280 = 66920
Step 240: 66920 + 280 = 67200
Step 241: 67200 + 280 = 67480
Step 242: 67480 + 280 = 67760
Step 243: 67760 + 280 = 68040
Step 244: 68040 + 280 = 68320
Step 245: 68320 + 280 = 68600
Step 246: 68600 + 280 = 68880
Step 247: 68880 + 280 = 69160
Step 248: 69160 + 280 = 69440
Step 249: 69440 + 280 = 69720
Step 250: 69720 + 280 = 70000
Step 251: 70000 + 280 = 70280
Step 252: 70280 + 280 = 70560
Step 253: 70560 + 280 = 70840
Step 254: 70840 + 280 = 71120
Step 255: 71120 + 280 = 71400
Step 256: 71400 + 280 = 71680

So, 280*256 = 71680