Let's roll up our sleeves and solve this. We have 879 and we're going to multiply it by 315, essentially adding 879 to itself 315 times.
Step 1: 0 + 879 = 879
Step 2: 879 + 879 = 1758
Step 3: 1758 + 879 = 2637
Step 4: 2637 + 879 = 3516
Step 5: 3516 + 879 = 4395
Step 6: 4395 + 879 = 5274
Step 7: 5274 + 879 = 6153
Step 8: 6153 + 879 = 7032
Step 9: 7032 + 879 = 7911
Step 10: 7911 + 879 = 8790
Step 11: 8790 + 879 = 9669
Step 12: 9669 + 879 = 10548
Step 13: 10548 + 879 = 11427
Step 14: 11427 + 879 = 12306
Step 15: 12306 + 879 = 13185
Step 16: 13185 + 879 = 14064
Step 17: 14064 + 879 = 14943
Step 18: 14943 + 879 = 15822
Step 19: 15822 + 879 = 16701
Step 20: 16701 + 879 = 17580
Step 21: 17580 + 879 = 18459
Step 22: 18459 + 879 = 19338
Step 23: 19338 + 879 = 20217
Step 24: 20217 + 879 = 21096
Step 25: 21096 + 879 = 21975
Step 26: 21975 + 879 = 22854
Step 27: 22854 + 879 = 23733
Step 28: 23733 + 879 = 24612
Step 29: 24612 + 879 = 25491
Step 30: 25491 + 879 = 26370
Step 31: 26370 + 879 = 27249
Step 32: 27249 + 879 = 28128
Step 33: 28128 + 879 = 29007
Step 34: 29007 + 879 = 29886
Step 35: 29886 + 879 = 30765
Step 36: 30765 + 879 = 31644
Step 37: 31644 + 879 = 32523
Step 38: 32523 + 879 = 33402
Step 39: 33402 + 879 = 34281
Step 40: 34281 + 879 = 35160
Step 41: 35160 + 879 = 36039
Step 42: 36039 + 879 = 36918
Step 43: 36918 + 879 = 37797
Step 44: 37797 + 879 = 38676
Step 45: 38676 + 879 = 39555
Step 46: 39555 + 879 = 40434
Step 47: 40434 + 879 = 41313
Step 48: 41313 + 879 = 42192
Step 49: 42192 + 879 = 43071
Step 50: 43071 + 879 = 43950
Step 51: 43950 + 879 = 44829
Step 52: 44829 + 879 = 45708
Step 53: 45708 + 879 = 46587
Step 54: 46587 + 879 = 47466
Step 55: 47466 + 879 = 48345
Step 56: 48345 + 879 = 49224
Step 57: 49224 + 879 = 50103
Step 58: 50103 + 879 = 50982
Step 59: 50982 + 879 = 51861
Step 60: 51861 + 879 = 52740
Step 61: 52740 + 879 = 53619
Step 62: 53619 + 879 = 54498
Step 63: 54498 + 879 = 55377
Step 64: 55377 + 879 = 56256
Step 65: 56256 + 879 = 57135
Step 66: 57135 + 879 = 58014
Step 67: 58014 + 879 = 58893
Step 68: 58893 + 879 = 59772
Step 69: 59772 + 879 = 60651
Step 70: 60651 + 879 = 61530
Step 71: 61530 + 879 = 62409
Step 72: 62409 + 879 = 63288
Step 73: 63288 + 879 = 64167
Step 74: 64167 + 879 = 65046
Step 75: 65046 + 879 = 65925
Step 76: 65925 + 879 = 66804
Step 77: 66804 + 879 = 67683
Step 78: 67683 + 879 = 68562
Step 79: 68562 + 879 = 69441
Step 80: 69441 + 879 = 70320
Step 81: 70320 + 879 = 71199
Step 82: 71199 + 879 = 72078
Step 83: 72078 + 879 = 72957
Step 84: 72957 + 879 = 73836
Step 85: 73836 + 879 = 74715
Step 86: 74715 + 879 = 75594
Step 87: 75594 + 879 = 76473
Step 88: 76473 + 879 = 77352
Step 89: 77352 + 879 = 78231
Step 90: 78231 + 879 = 79110
Step 91: 79110 + 879 = 79989
Step 92: 79989 + 879 = 80868
Step 93: 80868 + 879 = 81747
Step 94: 81747 + 879 = 82626
Step 95: 82626 + 879 = 83505
Step 96: 83505 + 879 = 84384
Step 97: 84384 + 879 = 85263
Step 98: 85263 + 879 = 86142
Step 99: 86142 + 879 = 87021
Step 100: 87021 + 879 = 87900
Step 101: 87900 + 879 = 88779
Step 102: 88779 + 879 = 89658
Step 103: 89658 + 879 = 90537
Step 104: 90537 + 879 = 91416
Step 105: 91416 + 879 = 92295
Step 106: 92295 + 879 = 93174
Step 107: 93174 + 879 = 94053
Step 108: 94053 + 879 = 94932
Step 109: 94932 + 879 = 95811
Step 110: 95811 + 879 = 96690
Step 111: 96690 + 879 = 97569
Step 112: 97569 + 879 = 98448
Step 113: 98448 + 879 = 99327
Step 114: 99327 + 879 = 100206
Step 115: 100206 + 879 = 101085
Step 116: 101085 + 879 = 101964
Step 117: 101964 + 879 = 102843
Step 118: 102843 + 879 = 103722
Step 119: 103722 + 879 = 104601
Step 120: 104601 + 879 = 105480
Step 121: 105480 + 879 = 106359
Step 122: 106359 + 879 = 107238
Step 123: 107238 + 879 = 108117
Step 124: 108117 + 879 = 108996
Step 125: 108996 + 879 = 109875
Step 126: 109875 + 879 = 110754
Step 127: 110754 + 879 = 111633
Step 128: 111633 + 879 = 112512
Step 129: 112512 + 879 = 113391
Step 130: 113391 + 879 = 114270
Step 131: 114270 + 879 = 115149
Step 132: 115149 + 879 = 116028
Step 133: 116028 + 879 = 116907
Step 134: 116907 + 879 = 117786
Step 135: 117786 + 879 = 118665
Step 136: 118665 + 879 = 119544
Step 137: 119544 + 879 = 120423
Step 138: 120423 + 879 = 121302
Step 139: 121302 + 879 = 122181
Step 140: 122181 + 879 = 123060
Step 141: 123060 + 879 = 123939
Step 142: 123939 + 879 = 124818
Step 143: 124818 + 879 = 125697
Step 144: 125697 + 879 = 126576
Step 145: 126576 + 879 = 127455
Step 146: 127455 + 879 = 128334
Step 147: 128334 + 879 = 129213
Step 148: 129213 + 879 = 130092
Step 149: 130092 + 879 = 130971
Step 150: 130971 + 879 = 131850
Step 151: 131850 + 879 = 132729
Step 152: 132729 + 879 = 133608
Step 153: 133608 + 879 = 134487
Step 154: 134487 + 879 = 135366
Step 155: 135366 + 879 = 136245
Step 156: 136245 + 879 = 137124
Step 157: 137124 + 879 = 138003
Step 158: 138003 + 879 = 138882
Step 159: 138882 + 879 = 139761
Step 160: 139761 + 879 = 140640
Step 161: 140640 + 879 = 141519
Step 162: 141519 + 879 = 142398
Step 163: 142398 + 879 = 143277
Step 164: 143277 + 879 = 144156
Step 165: 144156 + 879 = 145035
Step 166: 145035 + 879 = 145914
Step 167: 145914 + 879 = 146793
Step 168: 146793 + 879 = 147672
Step 169: 147672 + 879 = 148551
Step 170: 148551 + 879 = 149430
Step 171: 149430 + 879 = 150309
Step 172: 150309 + 879 = 151188
Step 173: 151188 + 879 = 152067
Step 174: 152067 + 879 = 152946
Step 175: 152946 + 879 = 153825
Step 176: 153825 + 879 = 154704
Step 177: 154704 + 879 = 155583
Step 178: 155583 + 879 = 156462
Step 179: 156462 + 879 = 157341
Step 180: 157341 + 879 = 158220
Step 181: 158220 + 879 = 159099
Step 182: 159099 + 879 = 159978
Step 183: 159978 + 879 = 160857
Step 184: 160857 + 879 = 161736
Step 185: 161736 + 879 = 162615
Step 186: 162615 + 879 = 163494
Step 187: 163494 + 879 = 164373
Step 188: 164373 + 879 = 165252
Step 189: 165252 + 879 = 166131
Step 190: 166131 + 879 = 167010
Step 191: 167010 + 879 = 167889
Step 192: 167889 + 879 = 168768
Step 193: 168768 + 879 = 169647
Step 194: 169647 + 879 = 170526
Step 195: 170526 + 879 = 171405
Step 196: 171405 + 879 = 172284
Step 197: 172284 + 879 = 173163
Step 198: 173163 + 879 = 174042
Step 199: 174042 + 879 = 174921
Step 200: 174921 + 879 = 175800
Step 201: 175800 + 879 = 176679
Step 202: 176679 + 879 = 177558
Step 203: 177558 + 879 = 178437
Step 204: 178437 + 879 = 179316
Step 205: 179316 + 879 = 180195
Step 206: 180195 + 879 = 181074
Step 207: 181074 + 879 = 181953
Step 208: 181953 + 879 = 182832
Step 209: 182832 + 879 = 183711
Step 210: 183711 + 879 = 184590
Step 211: 184590 + 879 = 185469
Step 212: 185469 + 879 = 186348
Step 213: 186348 + 879 = 187227
Step 214: 187227 + 879 = 188106
Step 215: 188106 + 879 = 188985
Step 216: 188985 + 879 = 189864
Step 217: 189864 + 879 = 190743
Step 218: 190743 + 879 = 191622
Step 219: 191622 + 879 = 192501
Step 220: 192501 + 879 = 193380
Step 221: 193380 + 879 = 194259
Step 222: 194259 + 879 = 195138
Step 223: 195138 + 879 = 196017
Step 224: 196017 + 879 = 196896
Step 225: 196896 + 879 = 197775
Step 226: 197775 + 879 = 198654
Step 227: 198654 + 879 = 199533
Step 228: 199533 + 879 = 200412
Step 229: 200412 + 879 = 201291
Step 230: 201291 + 879 = 202170
Step 231: 202170 + 879 = 203049
Step 232: 203049 + 879 = 203928
Step 233: 203928 + 879 = 204807
Step 234: 204807 + 879 = 205686
Step 235: 205686 + 879 = 206565
Step 236: 206565 + 879 = 207444
Step 237: 207444 + 879 = 208323
Step 238: 208323 + 879 = 209202
Step 239: 209202 + 879 = 210081
Step 240: 210081 + 879 = 210960
Step 241: 210960 + 879 = 211839
Step 242: 211839 + 879 = 212718
Step 243: 212718 + 879 = 213597
Step 244: 213597 + 879 = 214476
Step 245: 214476 + 879 = 215355
Step 246: 215355 + 879 = 216234
Step 247: 216234 + 879 = 217113
Step 248: 217113 + 879 = 217992
Step 249: 217992 + 879 = 218871
Step 250: 218871 + 879 = 219750
Step 251: 219750 + 879 = 220629
Step 252: 220629 + 879 = 221508
Step 253: 221508 + 879 = 222387
Step 254: 222387 + 879 = 223266
Step 255: 223266 + 879 = 224145
Step 256: 224145 + 879 = 225024
Step 257: 225024 + 879 = 225903
Step 258: 225903 + 879 = 226782
Step 259: 226782 + 879 = 227661
Step 260: 227661 + 879 = 228540
Step 261: 228540 + 879 = 229419
Step 262: 229419 + 879 = 230298
Step 263: 230298 + 879 = 231177
Step 264: 231177 + 879 = 232056
Step 265: 232056 + 879 = 232935
Step 266: 232935 + 879 = 233814
Step 267: 233814 + 879 = 234693
Step 268: 234693 + 879 = 235572
Step 269: 235572 + 879 = 236451
Step 270: 236451 + 879 = 237330
Step 271: 237330 + 879 = 238209
Step 272: 238209 + 879 = 239088
Step 273: 239088 + 879 = 239967
Step 274: 239967 + 879 = 240846
Step 275: 240846 + 879 = 241725
Step 276: 241725 + 879 = 242604
Step 277: 242604 + 879 = 243483
Step 278: 243483 + 879 = 244362
Step 279: 244362 + 879 = 245241
Step 280: 245241 + 879 = 246120
Step 281: 246120 + 879 = 246999
Step 282: 246999 + 879 = 247878
Step 283: 247878 + 879 = 248757
Step 284: 248757 + 879 = 249636
Step 285: 249636 + 879 = 250515
Step 286: 250515 + 879 = 251394
Step 287: 251394 + 879 = 252273
Step 288: 252273 + 879 = 253152
Step 289: 253152 + 879 = 254031
Step 290: 254031 + 879 = 254910
Step 291: 254910 + 879 = 255789
Step 292: 255789 + 879 = 256668
Step 293: 256668 + 879 = 257547
Step 294: 257547 + 879 = 258426
Step 295: 258426 + 879 = 259305
Step 296: 259305 + 879 = 260184
Step 297: 260184 + 879 = 261063
Step 298: 261063 + 879 = 261942
Step 299: 261942 + 879 = 262821
Step 300: 262821 + 879 = 263700
Step 301: 263700 + 879 = 264579
Step 302: 264579 + 879 = 265458
Step 303: 265458 + 879 = 266337
Step 304: 266337 + 879 = 267216
Step 305: 267216 + 879 = 268095
Step 306: 268095 + 879 = 268974
Step 307: 268974 + 879 = 269853
Step 308: 269853 + 879 = 270732
Step 309: 270732 + 879 = 271611
Step 310: 271611 + 879 = 272490
Step 311: 272490 + 879 = 273369
Step 312: 273369 + 879 = 274248
Step 313: 274248 + 879 = 275127
Step 314: 275127 + 879 = 276006
Step 315: 276006 + 879 = 276885

So, 879*315 = 276885