Let's roll up our sleeves and solve this. We have 336 and we're going to multiply it by 426, essentially adding 336 to itself 426 times.
Step 1: 0 + 336 = 336
Step 2: 336 + 336 = 672
Step 3: 672 + 336 = 1008
Step 4: 1008 + 336 = 1344
Step 5: 1344 + 336 = 1680
Step 6: 1680 + 336 = 2016
Step 7: 2016 + 336 = 2352
Step 8: 2352 + 336 = 2688
Step 9: 2688 + 336 = 3024
Step 10: 3024 + 336 = 3360
Step 11: 3360 + 336 = 3696
Step 12: 3696 + 336 = 4032
Step 13: 4032 + 336 = 4368
Step 14: 4368 + 336 = 4704
Step 15: 4704 + 336 = 5040
Step 16: 5040 + 336 = 5376
Step 17: 5376 + 336 = 5712
Step 18: 5712 + 336 = 6048
Step 19: 6048 + 336 = 6384
Step 20: 6384 + 336 = 6720
Step 21: 6720 + 336 = 7056
Step 22: 7056 + 336 = 7392
Step 23: 7392 + 336 = 7728
Step 24: 7728 + 336 = 8064
Step 25: 8064 + 336 = 8400
Step 26: 8400 + 336 = 8736
Step 27: 8736 + 336 = 9072
Step 28: 9072 + 336 = 9408
Step 29: 9408 + 336 = 9744
Step 30: 9744 + 336 = 10080
Step 31: 10080 + 336 = 10416
Step 32: 10416 + 336 = 10752
Step 33: 10752 + 336 = 11088
Step 34: 11088 + 336 = 11424
Step 35: 11424 + 336 = 11760
Step 36: 11760 + 336 = 12096
Step 37: 12096 + 336 = 12432
Step 38: 12432 + 336 = 12768
Step 39: 12768 + 336 = 13104
Step 40: 13104 + 336 = 13440
Step 41: 13440 + 336 = 13776
Step 42: 13776 + 336 = 14112
Step 43: 14112 + 336 = 14448
Step 44: 14448 + 336 = 14784
Step 45: 14784 + 336 = 15120
Step 46: 15120 + 336 = 15456
Step 47: 15456 + 336 = 15792
Step 48: 15792 + 336 = 16128
Step 49: 16128 + 336 = 16464
Step 50: 16464 + 336 = 16800
Step 51: 16800 + 336 = 17136
Step 52: 17136 + 336 = 17472
Step 53: 17472 + 336 = 17808
Step 54: 17808 + 336 = 18144
Step 55: 18144 + 336 = 18480
Step 56: 18480 + 336 = 18816
Step 57: 18816 + 336 = 19152
Step 58: 19152 + 336 = 19488
Step 59: 19488 + 336 = 19824
Step 60: 19824 + 336 = 20160
Step 61: 20160 + 336 = 20496
Step 62: 20496 + 336 = 20832
Step 63: 20832 + 336 = 21168
Step 64: 21168 + 336 = 21504
Step 65: 21504 + 336 = 21840
Step 66: 21840 + 336 = 22176
Step 67: 22176 + 336 = 22512
Step 68: 22512 + 336 = 22848
Step 69: 22848 + 336 = 23184
Step 70: 23184 + 336 = 23520
Step 71: 23520 + 336 = 23856
Step 72: 23856 + 336 = 24192
Step 73: 24192 + 336 = 24528
Step 74: 24528 + 336 = 24864
Step 75: 24864 + 336 = 25200
Step 76: 25200 + 336 = 25536
Step 77: 25536 + 336 = 25872
Step 78: 25872 + 336 = 26208
Step 79: 26208 + 336 = 26544
Step 80: 26544 + 336 = 26880
Step 81: 26880 + 336 = 27216
Step 82: 27216 + 336 = 27552
Step 83: 27552 + 336 = 27888
Step 84: 27888 + 336 = 28224
Step 85: 28224 + 336 = 28560
Step 86: 28560 + 336 = 28896
Step 87: 28896 + 336 = 29232
Step 88: 29232 + 336 = 29568
Step 89: 29568 + 336 = 29904
Step 90: 29904 + 336 = 30240
Step 91: 30240 + 336 = 30576
Step 92: 30576 + 336 = 30912
Step 93: 30912 + 336 = 31248
Step 94: 31248 + 336 = 31584
Step 95: 31584 + 336 = 31920
Step 96: 31920 + 336 = 32256
Step 97: 32256 + 336 = 32592
Step 98: 32592 + 336 = 32928
Step 99: 32928 + 336 = 33264
Step 100: 33264 + 336 = 33600
Step 101: 33600 + 336 = 33936
Step 102: 33936 + 336 = 34272
Step 103: 34272 + 336 = 34608
Step 104: 34608 + 336 = 34944
Step 105: 34944 + 336 = 35280
Step 106: 35280 + 336 = 35616
Step 107: 35616 + 336 = 35952
Step 108: 35952 + 336 = 36288
Step 109: 36288 + 336 = 36624
Step 110: 36624 + 336 = 36960
Step 111: 36960 + 336 = 37296
Step 112: 37296 + 336 = 37632
Step 113: 37632 + 336 = 37968
Step 114: 37968 + 336 = 38304
Step 115: 38304 + 336 = 38640
Step 116: 38640 + 336 = 38976
Step 117: 38976 + 336 = 39312
Step 118: 39312 + 336 = 39648
Step 119: 39648 + 336 = 39984
Step 120: 39984 + 336 = 40320
Step 121: 40320 + 336 = 40656
Step 122: 40656 + 336 = 40992
Step 123: 40992 + 336 = 41328
Step 124: 41328 + 336 = 41664
Step 125: 41664 + 336 = 42000
Step 126: 42000 + 336 = 42336
Step 127: 42336 + 336 = 42672
Step 128: 42672 + 336 = 43008
Step 129: 43008 + 336 = 43344
Step 130: 43344 + 336 = 43680
Step 131: 43680 + 336 = 44016
Step 132: 44016 + 336 = 44352
Step 133: 44352 + 336 = 44688
Step 134: 44688 + 336 = 45024
Step 135: 45024 + 336 = 45360
Step 136: 45360 + 336 = 45696
Step 137: 45696 + 336 = 46032
Step 138: 46032 + 336 = 46368
Step 139: 46368 + 336 = 46704
Step 140: 46704 + 336 = 47040
Step 141: 47040 + 336 = 47376
Step 142: 47376 + 336 = 47712
Step 143: 47712 + 336 = 48048
Step 144: 48048 + 336 = 48384
Step 145: 48384 + 336 = 48720
Step 146: 48720 + 336 = 49056
Step 147: 49056 + 336 = 49392
Step 148: 49392 + 336 = 49728
Step 149: 49728 + 336 = 50064
Step 150: 50064 + 336 = 50400
Step 151: 50400 + 336 = 50736
Step 152: 50736 + 336 = 51072
Step 153: 51072 + 336 = 51408
Step 154: 51408 + 336 = 51744
Step 155: 51744 + 336 = 52080
Step 156: 52080 + 336 = 52416
Step 157: 52416 + 336 = 52752
Step 158: 52752 + 336 = 53088
Step 159: 53088 + 336 = 53424
Step 160: 53424 + 336 = 53760
Step 161: 53760 + 336 = 54096
Step 162: 54096 + 336 = 54432
Step 163: 54432 + 336 = 54768
Step 164: 54768 + 336 = 55104
Step 165: 55104 + 336 = 55440
Step 166: 55440 + 336 = 55776
Step 167: 55776 + 336 = 56112
Step 168: 56112 + 336 = 56448
Step 169: 56448 + 336 = 56784
Step 170: 56784 + 336 = 57120
Step 171: 57120 + 336 = 57456
Step 172: 57456 + 336 = 57792
Step 173: 57792 + 336 = 58128
Step 174: 58128 + 336 = 58464
Step 175: 58464 + 336 = 58800
Step 176: 58800 + 336 = 59136
Step 177: 59136 + 336 = 59472
Step 178: 59472 + 336 = 59808
Step 179: 59808 + 336 = 60144
Step 180: 60144 + 336 = 60480
Step 181: 60480 + 336 = 60816
Step 182: 60816 + 336 = 61152
Step 183: 61152 + 336 = 61488
Step 184: 61488 + 336 = 61824
Step 185: 61824 + 336 = 62160
Step 186: 62160 + 336 = 62496
Step 187: 62496 + 336 = 62832
Step 188: 62832 + 336 = 63168
Step 189: 63168 + 336 = 63504
Step 190: 63504 + 336 = 63840
Step 191: 63840 + 336 = 64176
Step 192: 64176 + 336 = 64512
Step 193: 64512 + 336 = 64848
Step 194: 64848 + 336 = 65184
Step 195: 65184 + 336 = 65520
Step 196: 65520 + 336 = 65856
Step 197: 65856 + 336 = 66192
Step 198: 66192 + 336 = 66528
Step 199: 66528 + 336 = 66864
Step 200: 66864 + 336 = 67200
Step 201: 67200 + 336 = 67536
Step 202: 67536 + 336 = 67872
Step 203: 67872 + 336 = 68208
Step 204: 68208 + 336 = 68544
Step 205: 68544 + 336 = 68880
Step 206: 68880 + 336 = 69216
Step 207: 69216 + 336 = 69552
Step 208: 69552 + 336 = 69888
Step 209: 69888 + 336 = 70224
Step 210: 70224 + 336 = 70560
Step 211: 70560 + 336 = 70896
Step 212: 70896 + 336 = 71232
Step 213: 71232 + 336 = 71568
Step 214: 71568 + 336 = 71904
Step 215: 71904 + 336 = 72240
Step 216: 72240 + 336 = 72576
Step 217: 72576 + 336 = 72912
Step 218: 72912 + 336 = 73248
Step 219: 73248 + 336 = 73584
Step 220: 73584 + 336 = 73920
Step 221: 73920 + 336 = 74256
Step 222: 74256 + 336 = 74592
Step 223: 74592 + 336 = 74928
Step 224: 74928 + 336 = 75264
Step 225: 75264 + 336 = 75600
Step 226: 75600 + 336 = 75936
Step 227: 75936 + 336 = 76272
Step 228: 76272 + 336 = 76608
Step 229: 76608 + 336 = 76944
Step 230: 76944 + 336 = 77280
Step 231: 77280 + 336 = 77616
Step 232: 77616 + 336 = 77952
Step 233: 77952 + 336 = 78288
Step 234: 78288 + 336 = 78624
Step 235: 78624 + 336 = 78960
Step 236: 78960 + 336 = 79296
Step 237: 79296 + 336 = 79632
Step 238: 79632 + 336 = 79968
Step 239: 79968 + 336 = 80304
Step 240: 80304 + 336 = 80640
Step 241: 80640 + 336 = 80976
Step 242: 80976 + 336 = 81312
Step 243: 81312 + 336 = 81648
Step 244: 81648 + 336 = 81984
Step 245: 81984 + 336 = 82320
Step 246: 82320 + 336 = 82656
Step 247: 82656 + 336 = 82992
Step 248: 82992 + 336 = 83328
Step 249: 83328 + 336 = 83664
Step 250: 83664 + 336 = 84000
Step 251: 84000 + 336 = 84336
Step 252: 84336 + 336 = 84672
Step 253: 84672 + 336 = 85008
Step 254: 85008 + 336 = 85344
Step 255: 85344 + 336 = 85680
Step 256: 85680 + 336 = 86016
Step 257: 86016 + 336 = 86352
Step 258: 86352 + 336 = 86688
Step 259: 86688 + 336 = 87024
Step 260: 87024 + 336 = 87360
Step 261: 87360 + 336 = 87696
Step 262: 87696 + 336 = 88032
Step 263: 88032 + 336 = 88368
Step 264: 88368 + 336 = 88704
Step 265: 88704 + 336 = 89040
Step 266: 89040 + 336 = 89376
Step 267: 89376 + 336 = 89712
Step 268: 89712 + 336 = 90048
Step 269: 90048 + 336 = 90384
Step 270: 90384 + 336 = 90720
Step 271: 90720 + 336 = 91056
Step 272: 91056 + 336 = 91392
Step 273: 91392 + 336 = 91728
Step 274: 91728 + 336 = 92064
Step 275: 92064 + 336 = 92400
Step 276: 92400 + 336 = 92736
Step 277: 92736 + 336 = 93072
Step 278: 93072 + 336 = 93408
Step 279: 93408 + 336 = 93744
Step 280: 93744 + 336 = 94080
Step 281: 94080 + 336 = 94416
Step 282: 94416 + 336 = 94752
Step 283: 94752 + 336 = 95088
Step 284: 95088 + 336 = 95424
Step 285: 95424 + 336 = 95760
Step 286: 95760 + 336 = 96096
Step 287: 96096 + 336 = 96432
Step 288: 96432 + 336 = 96768
Step 289: 96768 + 336 = 97104
Step 290: 97104 + 336 = 97440
Step 291: 97440 + 336 = 97776
Step 292: 97776 + 336 = 98112
Step 293: 98112 + 336 = 98448
Step 294: 98448 + 336 = 98784
Step 295: 98784 + 336 = 99120
Step 296: 99120 + 336 = 99456
Step 297: 99456 + 336 = 99792
Step 298: 99792 + 336 = 100128
Step 299: 100128 + 336 = 100464
Step 300: 100464 + 336 = 100800
Step 301: 100800 + 336 = 101136
Step 302: 101136 + 336 = 101472
Step 303: 101472 + 336 = 101808
Step 304: 101808 + 336 = 102144
Step 305: 102144 + 336 = 102480
Step 306: 102480 + 336 = 102816
Step 307: 102816 + 336 = 103152
Step 308: 103152 + 336 = 103488
Step 309: 103488 + 336 = 103824
Step 310: 103824 + 336 = 104160
Step 311: 104160 + 336 = 104496
Step 312: 104496 + 336 = 104832
Step 313: 104832 + 336 = 105168
Step 314: 105168 + 336 = 105504
Step 315: 105504 + 336 = 105840
Step 316: 105840 + 336 = 106176
Step 317: 106176 + 336 = 106512
Step 318: 106512 + 336 = 106848
Step 319: 106848 + 336 = 107184
Step 320: 107184 + 336 = 107520
Step 321: 107520 + 336 = 107856
Step 322: 107856 + 336 = 108192
Step 323: 108192 + 336 = 108528
Step 324: 108528 + 336 = 108864
Step 325: 108864 + 336 = 109200
Step 326: 109200 + 336 = 109536
Step 327: 109536 + 336 = 109872
Step 328: 109872 + 336 = 110208
Step 329: 110208 + 336 = 110544
Step 330: 110544 + 336 = 110880
Step 331: 110880 + 336 = 111216
Step 332: 111216 + 336 = 111552
Step 333: 111552 + 336 = 111888
Step 334: 111888 + 336 = 112224
Step 335: 112224 + 336 = 112560
Step 336: 112560 + 336 = 112896
Step 337: 112896 + 336 = 113232
Step 338: 113232 + 336 = 113568
Step 339: 113568 + 336 = 113904
Step 340: 113904 + 336 = 114240
Step 341: 114240 + 336 = 114576
Step 342: 114576 + 336 = 114912
Step 343: 114912 + 336 = 115248
Step 344: 115248 + 336 = 115584
Step 345: 115584 + 336 = 115920
Step 346: 115920 + 336 = 116256
Step 347: 116256 + 336 = 116592
Step 348: 116592 + 336 = 116928
Step 349: 116928 + 336 = 117264
Step 350: 117264 + 336 = 117600
Step 351: 117600 + 336 = 117936
Step 352: 117936 + 336 = 118272
Step 353: 118272 + 336 = 118608
Step 354: 118608 + 336 = 118944
Step 355: 118944 + 336 = 119280
Step 356: 119280 + 336 = 119616
Step 357: 119616 + 336 = 119952
Step 358: 119952 + 336 = 120288
Step 359: 120288 + 336 = 120624
Step 360: 120624 + 336 = 120960
Step 361: 120960 + 336 = 121296
Step 362: 121296 + 336 = 121632
Step 363: 121632 + 336 = 121968
Step 364: 121968 + 336 = 122304
Step 365: 122304 + 336 = 122640
Step 366: 122640 + 336 = 122976
Step 367: 122976 + 336 = 123312
Step 368: 123312 + 336 = 123648
Step 369: 123648 + 336 = 123984
Step 370: 123984 + 336 = 124320
Step 371: 124320 + 336 = 124656
Step 372: 124656 + 336 = 124992
Step 373: 124992 + 336 = 125328
Step 374: 125328 + 336 = 125664
Step 375: 125664 + 336 = 126000
Step 376: 126000 + 336 = 126336
Step 377: 126336 + 336 = 126672
Step 378: 126672 + 336 = 127008
Step 379: 127008 + 336 = 127344
Step 380: 127344 + 336 = 127680
Step 381: 127680 + 336 = 128016
Step 382: 128016 + 336 = 128352
Step 383: 128352 + 336 = 128688
Step 384: 128688 + 336 = 129024
Step 385: 129024 + 336 = 129360
Step 386: 129360 + 336 = 129696
Step 387: 129696 + 336 = 130032
Step 388: 130032 + 336 = 130368
Step 389: 130368 + 336 = 130704
Step 390: 130704 + 336 = 131040
Step 391: 131040 + 336 = 131376
Step 392: 131376 + 336 = 131712
Step 393: 131712 + 336 = 132048
Step 394: 132048 + 336 = 132384
Step 395: 132384 + 336 = 132720
Step 396: 132720 + 336 = 133056
Step 397: 133056 + 336 = 133392
Step 398: 133392 + 336 = 133728
Step 399: 133728 + 336 = 134064
Step 400: 134064 + 336 = 134400
Step 401: 134400 + 336 = 134736
Step 402: 134736 + 336 = 135072
Step 403: 135072 + 336 = 135408
Step 404: 135408 + 336 = 135744
Step 405: 135744 + 336 = 136080
Step 406: 136080 + 336 = 136416
Step 407: 136416 + 336 = 136752
Step 408: 136752 + 336 = 137088
Step 409: 137088 + 336 = 137424
Step 410: 137424 + 336 = 137760
Step 411: 137760 + 336 = 138096
Step 412: 138096 + 336 = 138432
Step 413: 138432 + 336 = 138768
Step 414: 138768 + 336 = 139104
Step 415: 139104 + 336 = 139440
Step 416: 139440 + 336 = 139776
Step 417: 139776 + 336 = 140112
Step 418: 140112 + 336 = 140448
Step 419: 140448 + 336 = 140784
Step 420: 140784 + 336 = 141120
Step 421: 141120 + 336 = 141456
Step 422: 141456 + 336 = 141792
Step 423: 141792 + 336 = 142128
Step 424: 142128 + 336 = 142464
Step 425: 142464 + 336 = 142800
Step 426: 142800 + 336 = 143136

So, 336*426 = 143136