OK, let's crack this. We're given 816 and our task is to multiply it by 345. Essentially, we'll be adding 816 to itself 345 times.
Step 1: 0 + 816 = 816
Step 2: 816 + 816 = 1632
Step 3: 1632 + 816 = 2448
Step 4: 2448 + 816 = 3264
Step 5: 3264 + 816 = 4080
Step 6: 4080 + 816 = 4896
Step 7: 4896 + 816 = 5712
Step 8: 5712 + 816 = 6528
Step 9: 6528 + 816 = 7344
Step 10: 7344 + 816 = 8160
Step 11: 8160 + 816 = 8976
Step 12: 8976 + 816 = 9792
Step 13: 9792 + 816 = 10608
Step 14: 10608 + 816 = 11424
Step 15: 11424 + 816 = 12240
Step 16: 12240 + 816 = 13056
Step 17: 13056 + 816 = 13872
Step 18: 13872 + 816 = 14688
Step 19: 14688 + 816 = 15504
Step 20: 15504 + 816 = 16320
Step 21: 16320 + 816 = 17136
Step 22: 17136 + 816 = 17952
Step 23: 17952 + 816 = 18768
Step 24: 18768 + 816 = 19584
Step 25: 19584 + 816 = 20400
Step 26: 20400 + 816 = 21216
Step 27: 21216 + 816 = 22032
Step 28: 22032 + 816 = 22848
Step 29: 22848 + 816 = 23664
Step 30: 23664 + 816 = 24480
Step 31: 24480 + 816 = 25296
Step 32: 25296 + 816 = 26112
Step 33: 26112 + 816 = 26928
Step 34: 26928 + 816 = 27744
Step 35: 27744 + 816 = 28560
Step 36: 28560 + 816 = 29376
Step 37: 29376 + 816 = 30192
Step 38: 30192 + 816 = 31008
Step 39: 31008 + 816 = 31824
Step 40: 31824 + 816 = 32640
Step 41: 32640 + 816 = 33456
Step 42: 33456 + 816 = 34272
Step 43: 34272 + 816 = 35088
Step 44: 35088 + 816 = 35904
Step 45: 35904 + 816 = 36720
Step 46: 36720 + 816 = 37536
Step 47: 37536 + 816 = 38352
Step 48: 38352 + 816 = 39168
Step 49: 39168 + 816 = 39984
Step 50: 39984 + 816 = 40800
Step 51: 40800 + 816 = 41616
Step 52: 41616 + 816 = 42432
Step 53: 42432 + 816 = 43248
Step 54: 43248 + 816 = 44064
Step 55: 44064 + 816 = 44880
Step 56: 44880 + 816 = 45696
Step 57: 45696 + 816 = 46512
Step 58: 46512 + 816 = 47328
Step 59: 47328 + 816 = 48144
Step 60: 48144 + 816 = 48960
Step 61: 48960 + 816 = 49776
Step 62: 49776 + 816 = 50592
Step 63: 50592 + 816 = 51408
Step 64: 51408 + 816 = 52224
Step 65: 52224 + 816 = 53040
Step 66: 53040 + 816 = 53856
Step 67: 53856 + 816 = 54672
Step 68: 54672 + 816 = 55488
Step 69: 55488 + 816 = 56304
Step 70: 56304 + 816 = 57120
Step 71: 57120 + 816 = 57936
Step 72: 57936 + 816 = 58752
Step 73: 58752 + 816 = 59568
Step 74: 59568 + 816 = 60384
Step 75: 60384 + 816 = 61200
Step 76: 61200 + 816 = 62016
Step 77: 62016 + 816 = 62832
Step 78: 62832 + 816 = 63648
Step 79: 63648 + 816 = 64464
Step 80: 64464 + 816 = 65280
Step 81: 65280 + 816 = 66096
Step 82: 66096 + 816 = 66912
Step 83: 66912 + 816 = 67728
Step 84: 67728 + 816 = 68544
Step 85: 68544 + 816 = 69360
Step 86: 69360 + 816 = 70176
Step 87: 70176 + 816 = 70992
Step 88: 70992 + 816 = 71808
Step 89: 71808 + 816 = 72624
Step 90: 72624 + 816 = 73440
Step 91: 73440 + 816 = 74256
Step 92: 74256 + 816 = 75072
Step 93: 75072 + 816 = 75888
Step 94: 75888 + 816 = 76704
Step 95: 76704 + 816 = 77520
Step 96: 77520 + 816 = 78336
Step 97: 78336 + 816 = 79152
Step 98: 79152 + 816 = 79968
Step 99: 79968 + 816 = 80784
Step 100: 80784 + 816 = 81600
Step 101: 81600 + 816 = 82416
Step 102: 82416 + 816 = 83232
Step 103: 83232 + 816 = 84048
Step 104: 84048 + 816 = 84864
Step 105: 84864 + 816 = 85680
Step 106: 85680 + 816 = 86496
Step 107: 86496 + 816 = 87312
Step 108: 87312 + 816 = 88128
Step 109: 88128 + 816 = 88944
Step 110: 88944 + 816 = 89760
Step 111: 89760 + 816 = 90576
Step 112: 90576 + 816 = 91392
Step 113: 91392 + 816 = 92208
Step 114: 92208 + 816 = 93024
Step 115: 93024 + 816 = 93840
Step 116: 93840 + 816 = 94656
Step 117: 94656 + 816 = 95472
Step 118: 95472 + 816 = 96288
Step 119: 96288 + 816 = 97104
Step 120: 97104 + 816 = 97920
Step 121: 97920 + 816 = 98736
Step 122: 98736 + 816 = 99552
Step 123: 99552 + 816 = 100368
Step 124: 100368 + 816 = 101184
Step 125: 101184 + 816 = 102000
Step 126: 102000 + 816 = 102816
Step 127: 102816 + 816 = 103632
Step 128: 103632 + 816 = 104448
Step 129: 104448 + 816 = 105264
Step 130: 105264 + 816 = 106080
Step 131: 106080 + 816 = 106896
Step 132: 106896 + 816 = 107712
Step 133: 107712 + 816 = 108528
Step 134: 108528 + 816 = 109344
Step 135: 109344 + 816 = 110160
Step 136: 110160 + 816 = 110976
Step 137: 110976 + 816 = 111792
Step 138: 111792 + 816 = 112608
Step 139: 112608 + 816 = 113424
Step 140: 113424 + 816 = 114240
Step 141: 114240 + 816 = 115056
Step 142: 115056 + 816 = 115872
Step 143: 115872 + 816 = 116688
Step 144: 116688 + 816 = 117504
Step 145: 117504 + 816 = 118320
Step 146: 118320 + 816 = 119136
Step 147: 119136 + 816 = 119952
Step 148: 119952 + 816 = 120768
Step 149: 120768 + 816 = 121584
Step 150: 121584 + 816 = 122400
Step 151: 122400 + 816 = 123216
Step 152: 123216 + 816 = 124032
Step 153: 124032 + 816 = 124848
Step 154: 124848 + 816 = 125664
Step 155: 125664 + 816 = 126480
Step 156: 126480 + 816 = 127296
Step 157: 127296 + 816 = 128112
Step 158: 128112 + 816 = 128928
Step 159: 128928 + 816 = 129744
Step 160: 129744 + 816 = 130560
Step 161: 130560 + 816 = 131376
Step 162: 131376 + 816 = 132192
Step 163: 132192 + 816 = 133008
Step 164: 133008 + 816 = 133824
Step 165: 133824 + 816 = 134640
Step 166: 134640 + 816 = 135456
Step 167: 135456 + 816 = 136272
Step 168: 136272 + 816 = 137088
Step 169: 137088 + 816 = 137904
Step 170: 137904 + 816 = 138720
Step 171: 138720 + 816 = 139536
Step 172: 139536 + 816 = 140352
Step 173: 140352 + 816 = 141168
Step 174: 141168 + 816 = 141984
Step 175: 141984 + 816 = 142800
Step 176: 142800 + 816 = 143616
Step 177: 143616 + 816 = 144432
Step 178: 144432 + 816 = 145248
Step 179: 145248 + 816 = 146064
Step 180: 146064 + 816 = 146880
Step 181: 146880 + 816 = 147696
Step 182: 147696 + 816 = 148512
Step 183: 148512 + 816 = 149328
Step 184: 149328 + 816 = 150144
Step 185: 150144 + 816 = 150960
Step 186: 150960 + 816 = 151776
Step 187: 151776 + 816 = 152592
Step 188: 152592 + 816 = 153408
Step 189: 153408 + 816 = 154224
Step 190: 154224 + 816 = 155040
Step 191: 155040 + 816 = 155856
Step 192: 155856 + 816 = 156672
Step 193: 156672 + 816 = 157488
Step 194: 157488 + 816 = 158304
Step 195: 158304 + 816 = 159120
Step 196: 159120 + 816 = 159936
Step 197: 159936 + 816 = 160752
Step 198: 160752 + 816 = 161568
Step 199: 161568 + 816 = 162384
Step 200: 162384 + 816 = 163200
Step 201: 163200 + 816 = 164016
Step 202: 164016 + 816 = 164832
Step 203: 164832 + 816 = 165648
Step 204: 165648 + 816 = 166464
Step 205: 166464 + 816 = 167280
Step 206: 167280 + 816 = 168096
Step 207: 168096 + 816 = 168912
Step 208: 168912 + 816 = 169728
Step 209: 169728 + 816 = 170544
Step 210: 170544 + 816 = 171360
Step 211: 171360 + 816 = 172176
Step 212: 172176 + 816 = 172992
Step 213: 172992 + 816 = 173808
Step 214: 173808 + 816 = 174624
Step 215: 174624 + 816 = 175440
Step 216: 175440 + 816 = 176256
Step 217: 176256 + 816 = 177072
Step 218: 177072 + 816 = 177888
Step 219: 177888 + 816 = 178704
Step 220: 178704 + 816 = 179520
Step 221: 179520 + 816 = 180336
Step 222: 180336 + 816 = 181152
Step 223: 181152 + 816 = 181968
Step 224: 181968 + 816 = 182784
Step 225: 182784 + 816 = 183600
Step 226: 183600 + 816 = 184416
Step 227: 184416 + 816 = 185232
Step 228: 185232 + 816 = 186048
Step 229: 186048 + 816 = 186864
Step 230: 186864 + 816 = 187680
Step 231: 187680 + 816 = 188496
Step 232: 188496 + 816 = 189312
Step 233: 189312 + 816 = 190128
Step 234: 190128 + 816 = 190944
Step 235: 190944 + 816 = 191760
Step 236: 191760 + 816 = 192576
Step 237: 192576 + 816 = 193392
Step 238: 193392 + 816 = 194208
Step 239: 194208 + 816 = 195024
Step 240: 195024 + 816 = 195840
Step 241: 195840 + 816 = 196656
Step 242: 196656 + 816 = 197472
Step 243: 197472 + 816 = 198288
Step 244: 198288 + 816 = 199104
Step 245: 199104 + 816 = 199920
Step 246: 199920 + 816 = 200736
Step 247: 200736 + 816 = 201552
Step 248: 201552 + 816 = 202368
Step 249: 202368 + 816 = 203184
Step 250: 203184 + 816 = 204000
Step 251: 204000 + 816 = 204816
Step 252: 204816 + 816 = 205632
Step 253: 205632 + 816 = 206448
Step 254: 206448 + 816 = 207264
Step 255: 207264 + 816 = 208080
Step 256: 208080 + 816 = 208896
Step 257: 208896 + 816 = 209712
Step 258: 209712 + 816 = 210528
Step 259: 210528 + 816 = 211344
Step 260: 211344 + 816 = 212160
Step 261: 212160 + 816 = 212976
Step 262: 212976 + 816 = 213792
Step 263: 213792 + 816 = 214608
Step 264: 214608 + 816 = 215424
Step 265: 215424 + 816 = 216240
Step 266: 216240 + 816 = 217056
Step 267: 217056 + 816 = 217872
Step 268: 217872 + 816 = 218688
Step 269: 218688 + 816 = 219504
Step 270: 219504 + 816 = 220320
Step 271: 220320 + 816 = 221136
Step 272: 221136 + 816 = 221952
Step 273: 221952 + 816 = 222768
Step 274: 222768 + 816 = 223584
Step 275: 223584 + 816 = 224400
Step 276: 224400 + 816 = 225216
Step 277: 225216 + 816 = 226032
Step 278: 226032 + 816 = 226848
Step 279: 226848 + 816 = 227664
Step 280: 227664 + 816 = 228480
Step 281: 228480 + 816 = 229296
Step 282: 229296 + 816 = 230112
Step 283: 230112 + 816 = 230928
Step 284: 230928 + 816 = 231744
Step 285: 231744 + 816 = 232560
Step 286: 232560 + 816 = 233376
Step 287: 233376 + 816 = 234192
Step 288: 234192 + 816 = 235008
Step 289: 235008 + 816 = 235824
Step 290: 235824 + 816 = 236640
Step 291: 236640 + 816 = 237456
Step 292: 237456 + 816 = 238272
Step 293: 238272 + 816 = 239088
Step 294: 239088 + 816 = 239904
Step 295: 239904 + 816 = 240720
Step 296: 240720 + 816 = 241536
Step 297: 241536 + 816 = 242352
Step 298: 242352 + 816 = 243168
Step 299: 243168 + 816 = 243984
Step 300: 243984 + 816 = 244800
Step 301: 244800 + 816 = 245616
Step 302: 245616 + 816 = 246432
Step 303: 246432 + 816 = 247248
Step 304: 247248 + 816 = 248064
Step 305: 248064 + 816 = 248880
Step 306: 248880 + 816 = 249696
Step 307: 249696 + 816 = 250512
Step 308: 250512 + 816 = 251328
Step 309: 251328 + 816 = 252144
Step 310: 252144 + 816 = 252960
Step 311: 252960 + 816 = 253776
Step 312: 253776 + 816 = 254592
Step 313: 254592 + 816 = 255408
Step 314: 255408 + 816 = 256224
Step 315: 256224 + 816 = 257040
Step 316: 257040 + 816 = 257856
Step 317: 257856 + 816 = 258672
Step 318: 258672 + 816 = 259488
Step 319: 259488 + 816 = 260304
Step 320: 260304 + 816 = 261120
Step 321: 261120 + 816 = 261936
Step 322: 261936 + 816 = 262752
Step 323: 262752 + 816 = 263568
Step 324: 263568 + 816 = 264384
Step 325: 264384 + 816 = 265200
Step 326: 265200 + 816 = 266016
Step 327: 266016 + 816 = 266832
Step 328: 266832 + 816 = 267648
Step 329: 267648 + 816 = 268464
Step 330: 268464 + 816 = 269280
Step 331: 269280 + 816 = 270096
Step 332: 270096 + 816 = 270912
Step 333: 270912 + 816 = 271728
Step 334: 271728 + 816 = 272544
Step 335: 272544 + 816 = 273360
Step 336: 273360 + 816 = 274176
Step 337: 274176 + 816 = 274992
Step 338: 274992 + 816 = 275808
Step 339: 275808 + 816 = 276624
Step 340: 276624 + 816 = 277440
Step 341: 277440 + 816 = 278256
Step 342: 278256 + 816 = 279072
Step 343: 279072 + 816 = 279888
Step 344: 279888 + 816 = 280704
Step 345: 280704 + 816 = 281520

So, 816*345 = 281520