Let's get this math done. We have 624 and we're going to multiply it by 345. This is the same as taking 624 and adding it to itself 345 times.
Step 1: 0 + 624 = 624
Step 2: 624 + 624 = 1248
Step 3: 1248 + 624 = 1872
Step 4: 1872 + 624 = 2496
Step 5: 2496 + 624 = 3120
Step 6: 3120 + 624 = 3744
Step 7: 3744 + 624 = 4368
Step 8: 4368 + 624 = 4992
Step 9: 4992 + 624 = 5616
Step 10: 5616 + 624 = 6240
Step 11: 6240 + 624 = 6864
Step 12: 6864 + 624 = 7488
Step 13: 7488 + 624 = 8112
Step 14: 8112 + 624 = 8736
Step 15: 8736 + 624 = 9360
Step 16: 9360 + 624 = 9984
Step 17: 9984 + 624 = 10608
Step 18: 10608 + 624 = 11232
Step 19: 11232 + 624 = 11856
Step 20: 11856 + 624 = 12480
Step 21: 12480 + 624 = 13104
Step 22: 13104 + 624 = 13728
Step 23: 13728 + 624 = 14352
Step 24: 14352 + 624 = 14976
Step 25: 14976 + 624 = 15600
Step 26: 15600 + 624 = 16224
Step 27: 16224 + 624 = 16848
Step 28: 16848 + 624 = 17472
Step 29: 17472 + 624 = 18096
Step 30: 18096 + 624 = 18720
Step 31: 18720 + 624 = 19344
Step 32: 19344 + 624 = 19968
Step 33: 19968 + 624 = 20592
Step 34: 20592 + 624 = 21216
Step 35: 21216 + 624 = 21840
Step 36: 21840 + 624 = 22464
Step 37: 22464 + 624 = 23088
Step 38: 23088 + 624 = 23712
Step 39: 23712 + 624 = 24336
Step 40: 24336 + 624 = 24960
Step 41: 24960 + 624 = 25584
Step 42: 25584 + 624 = 26208
Step 43: 26208 + 624 = 26832
Step 44: 26832 + 624 = 27456
Step 45: 27456 + 624 = 28080
Step 46: 28080 + 624 = 28704
Step 47: 28704 + 624 = 29328
Step 48: 29328 + 624 = 29952
Step 49: 29952 + 624 = 30576
Step 50: 30576 + 624 = 31200
Step 51: 31200 + 624 = 31824
Step 52: 31824 + 624 = 32448
Step 53: 32448 + 624 = 33072
Step 54: 33072 + 624 = 33696
Step 55: 33696 + 624 = 34320
Step 56: 34320 + 624 = 34944
Step 57: 34944 + 624 = 35568
Step 58: 35568 + 624 = 36192
Step 59: 36192 + 624 = 36816
Step 60: 36816 + 624 = 37440
Step 61: 37440 + 624 = 38064
Step 62: 38064 + 624 = 38688
Step 63: 38688 + 624 = 39312
Step 64: 39312 + 624 = 39936
Step 65: 39936 + 624 = 40560
Step 66: 40560 + 624 = 41184
Step 67: 41184 + 624 = 41808
Step 68: 41808 + 624 = 42432
Step 69: 42432 + 624 = 43056
Step 70: 43056 + 624 = 43680
Step 71: 43680 + 624 = 44304
Step 72: 44304 + 624 = 44928
Step 73: 44928 + 624 = 45552
Step 74: 45552 + 624 = 46176
Step 75: 46176 + 624 = 46800
Step 76: 46800 + 624 = 47424
Step 77: 47424 + 624 = 48048
Step 78: 48048 + 624 = 48672
Step 79: 48672 + 624 = 49296
Step 80: 49296 + 624 = 49920
Step 81: 49920 + 624 = 50544
Step 82: 50544 + 624 = 51168
Step 83: 51168 + 624 = 51792
Step 84: 51792 + 624 = 52416
Step 85: 52416 + 624 = 53040
Step 86: 53040 + 624 = 53664
Step 87: 53664 + 624 = 54288
Step 88: 54288 + 624 = 54912
Step 89: 54912 + 624 = 55536
Step 90: 55536 + 624 = 56160
Step 91: 56160 + 624 = 56784
Step 92: 56784 + 624 = 57408
Step 93: 57408 + 624 = 58032
Step 94: 58032 + 624 = 58656
Step 95: 58656 + 624 = 59280
Step 96: 59280 + 624 = 59904
Step 97: 59904 + 624 = 60528
Step 98: 60528 + 624 = 61152
Step 99: 61152 + 624 = 61776
Step 100: 61776 + 624 = 62400
Step 101: 62400 + 624 = 63024
Step 102: 63024 + 624 = 63648
Step 103: 63648 + 624 = 64272
Step 104: 64272 + 624 = 64896
Step 105: 64896 + 624 = 65520
Step 106: 65520 + 624 = 66144
Step 107: 66144 + 624 = 66768
Step 108: 66768 + 624 = 67392
Step 109: 67392 + 624 = 68016
Step 110: 68016 + 624 = 68640
Step 111: 68640 + 624 = 69264
Step 112: 69264 + 624 = 69888
Step 113: 69888 + 624 = 70512
Step 114: 70512 + 624 = 71136
Step 115: 71136 + 624 = 71760
Step 116: 71760 + 624 = 72384
Step 117: 72384 + 624 = 73008
Step 118: 73008 + 624 = 73632
Step 119: 73632 + 624 = 74256
Step 120: 74256 + 624 = 74880
Step 121: 74880 + 624 = 75504
Step 122: 75504 + 624 = 76128
Step 123: 76128 + 624 = 76752
Step 124: 76752 + 624 = 77376
Step 125: 77376 + 624 = 78000
Step 126: 78000 + 624 = 78624
Step 127: 78624 + 624 = 79248
Step 128: 79248 + 624 = 79872
Step 129: 79872 + 624 = 80496
Step 130: 80496 + 624 = 81120
Step 131: 81120 + 624 = 81744
Step 132: 81744 + 624 = 82368
Step 133: 82368 + 624 = 82992
Step 134: 82992 + 624 = 83616
Step 135: 83616 + 624 = 84240
Step 136: 84240 + 624 = 84864
Step 137: 84864 + 624 = 85488
Step 138: 85488 + 624 = 86112
Step 139: 86112 + 624 = 86736
Step 140: 86736 + 624 = 87360
Step 141: 87360 + 624 = 87984
Step 142: 87984 + 624 = 88608
Step 143: 88608 + 624 = 89232
Step 144: 89232 + 624 = 89856
Step 145: 89856 + 624 = 90480
Step 146: 90480 + 624 = 91104
Step 147: 91104 + 624 = 91728
Step 148: 91728 + 624 = 92352
Step 149: 92352 + 624 = 92976
Step 150: 92976 + 624 = 93600
Step 151: 93600 + 624 = 94224
Step 152: 94224 + 624 = 94848
Step 153: 94848 + 624 = 95472
Step 154: 95472 + 624 = 96096
Step 155: 96096 + 624 = 96720
Step 156: 96720 + 624 = 97344
Step 157: 97344 + 624 = 97968
Step 158: 97968 + 624 = 98592
Step 159: 98592 + 624 = 99216
Step 160: 99216 + 624 = 99840
Step 161: 99840 + 624 = 100464
Step 162: 100464 + 624 = 101088
Step 163: 101088 + 624 = 101712
Step 164: 101712 + 624 = 102336
Step 165: 102336 + 624 = 102960
Step 166: 102960 + 624 = 103584
Step 167: 103584 + 624 = 104208
Step 168: 104208 + 624 = 104832
Step 169: 104832 + 624 = 105456
Step 170: 105456 + 624 = 106080
Step 171: 106080 + 624 = 106704
Step 172: 106704 + 624 = 107328
Step 173: 107328 + 624 = 107952
Step 174: 107952 + 624 = 108576
Step 175: 108576 + 624 = 109200
Step 176: 109200 + 624 = 109824
Step 177: 109824 + 624 = 110448
Step 178: 110448 + 624 = 111072
Step 179: 111072 + 624 = 111696
Step 180: 111696 + 624 = 112320
Step 181: 112320 + 624 = 112944
Step 182: 112944 + 624 = 113568
Step 183: 113568 + 624 = 114192
Step 184: 114192 + 624 = 114816
Step 185: 114816 + 624 = 115440
Step 186: 115440 + 624 = 116064
Step 187: 116064 + 624 = 116688
Step 188: 116688 + 624 = 117312
Step 189: 117312 + 624 = 117936
Step 190: 117936 + 624 = 118560
Step 191: 118560 + 624 = 119184
Step 192: 119184 + 624 = 119808
Step 193: 119808 + 624 = 120432
Step 194: 120432 + 624 = 121056
Step 195: 121056 + 624 = 121680
Step 196: 121680 + 624 = 122304
Step 197: 122304 + 624 = 122928
Step 198: 122928 + 624 = 123552
Step 199: 123552 + 624 = 124176
Step 200: 124176 + 624 = 124800
Step 201: 124800 + 624 = 125424
Step 202: 125424 + 624 = 126048
Step 203: 126048 + 624 = 126672
Step 204: 126672 + 624 = 127296
Step 205: 127296 + 624 = 127920
Step 206: 127920 + 624 = 128544
Step 207: 128544 + 624 = 129168
Step 208: 129168 + 624 = 129792
Step 209: 129792 + 624 = 130416
Step 210: 130416 + 624 = 131040
Step 211: 131040 + 624 = 131664
Step 212: 131664 + 624 = 132288
Step 213: 132288 + 624 = 132912
Step 214: 132912 + 624 = 133536
Step 215: 133536 + 624 = 134160
Step 216: 134160 + 624 = 134784
Step 217: 134784 + 624 = 135408
Step 218: 135408 + 624 = 136032
Step 219: 136032 + 624 = 136656
Step 220: 136656 + 624 = 137280
Step 221: 137280 + 624 = 137904
Step 222: 137904 + 624 = 138528
Step 223: 138528 + 624 = 139152
Step 224: 139152 + 624 = 139776
Step 225: 139776 + 624 = 140400
Step 226: 140400 + 624 = 141024
Step 227: 141024 + 624 = 141648
Step 228: 141648 + 624 = 142272
Step 229: 142272 + 624 = 142896
Step 230: 142896 + 624 = 143520
Step 231: 143520 + 624 = 144144
Step 232: 144144 + 624 = 144768
Step 233: 144768 + 624 = 145392
Step 234: 145392 + 624 = 146016
Step 235: 146016 + 624 = 146640
Step 236: 146640 + 624 = 147264
Step 237: 147264 + 624 = 147888
Step 238: 147888 + 624 = 148512
Step 239: 148512 + 624 = 149136
Step 240: 149136 + 624 = 149760
Step 241: 149760 + 624 = 150384
Step 242: 150384 + 624 = 151008
Step 243: 151008 + 624 = 151632
Step 244: 151632 + 624 = 152256
Step 245: 152256 + 624 = 152880
Step 246: 152880 + 624 = 153504
Step 247: 153504 + 624 = 154128
Step 248: 154128 + 624 = 154752
Step 249: 154752 + 624 = 155376
Step 250: 155376 + 624 = 156000
Step 251: 156000 + 624 = 156624
Step 252: 156624 + 624 = 157248
Step 253: 157248 + 624 = 157872
Step 254: 157872 + 624 = 158496
Step 255: 158496 + 624 = 159120
Step 256: 159120 + 624 = 159744
Step 257: 159744 + 624 = 160368
Step 258: 160368 + 624 = 160992
Step 259: 160992 + 624 = 161616
Step 260: 161616 + 624 = 162240
Step 261: 162240 + 624 = 162864
Step 262: 162864 + 624 = 163488
Step 263: 163488 + 624 = 164112
Step 264: 164112 + 624 = 164736
Step 265: 164736 + 624 = 165360
Step 266: 165360 + 624 = 165984
Step 267: 165984 + 624 = 166608
Step 268: 166608 + 624 = 167232
Step 269: 167232 + 624 = 167856
Step 270: 167856 + 624 = 168480
Step 271: 168480 + 624 = 169104
Step 272: 169104 + 624 = 169728
Step 273: 169728 + 624 = 170352
Step 274: 170352 + 624 = 170976
Step 275: 170976 + 624 = 171600
Step 276: 171600 + 624 = 172224
Step 277: 172224 + 624 = 172848
Step 278: 172848 + 624 = 173472
Step 279: 173472 + 624 = 174096
Step 280: 174096 + 624 = 174720
Step 281: 174720 + 624 = 175344
Step 282: 175344 + 624 = 175968
Step 283: 175968 + 624 = 176592
Step 284: 176592 + 624 = 177216
Step 285: 177216 + 624 = 177840
Step 286: 177840 + 624 = 178464
Step 287: 178464 + 624 = 179088
Step 288: 179088 + 624 = 179712
Step 289: 179712 + 624 = 180336
Step 290: 180336 + 624 = 180960
Step 291: 180960 + 624 = 181584
Step 292: 181584 + 624 = 182208
Step 293: 182208 + 624 = 182832
Step 294: 182832 + 624 = 183456
Step 295: 183456 + 624 = 184080
Step 296: 184080 + 624 = 184704
Step 297: 184704 + 624 = 185328
Step 298: 185328 + 624 = 185952
Step 299: 185952 + 624 = 186576
Step 300: 186576 + 624 = 187200
Step 301: 187200 + 624 = 187824
Step 302: 187824 + 624 = 188448
Step 303: 188448 + 624 = 189072
Step 304: 189072 + 624 = 189696
Step 305: 189696 + 624 = 190320
Step 306: 190320 + 624 = 190944
Step 307: 190944 + 624 = 191568
Step 308: 191568 + 624 = 192192
Step 309: 192192 + 624 = 192816
Step 310: 192816 + 624 = 193440
Step 311: 193440 + 624 = 194064
Step 312: 194064 + 624 = 194688
Step 313: 194688 + 624 = 195312
Step 314: 195312 + 624 = 195936
Step 315: 195936 + 624 = 196560
Step 316: 196560 + 624 = 197184
Step 317: 197184 + 624 = 197808
Step 318: 197808 + 624 = 198432
Step 319: 198432 + 624 = 199056
Step 320: 199056 + 624 = 199680
Step 321: 199680 + 624 = 200304
Step 322: 200304 + 624 = 200928
Step 323: 200928 + 624 = 201552
Step 324: 201552 + 624 = 202176
Step 325: 202176 + 624 = 202800
Step 326: 202800 + 624 = 203424
Step 327: 203424 + 624 = 204048
Step 328: 204048 + 624 = 204672
Step 329: 204672 + 624 = 205296
Step 330: 205296 + 624 = 205920
Step 331: 205920 + 624 = 206544
Step 332: 206544 + 624 = 207168
Step 333: 207168 + 624 = 207792
Step 334: 207792 + 624 = 208416
Step 335: 208416 + 624 = 209040
Step 336: 209040 + 624 = 209664
Step 337: 209664 + 624 = 210288
Step 338: 210288 + 624 = 210912
Step 339: 210912 + 624 = 211536
Step 340: 211536 + 624 = 212160
Step 341: 212160 + 624 = 212784
Step 342: 212784 + 624 = 213408
Step 343: 213408 + 624 = 214032
Step 344: 214032 + 624 = 214656
Step 345: 214656 + 624 = 215280

So, 624*345 = 215280