Let's get this math done. We have 84 and we're going to multiply it by 261. This is the same as taking 84 and adding it to itself 261 times.
Step 1: 0 + 84 = 84
Step 2: 84 + 84 = 168
Step 3: 168 + 84 = 252
Step 4: 252 + 84 = 336
Step 5: 336 + 84 = 420
Step 6: 420 + 84 = 504
Step 7: 504 + 84 = 588
Step 8: 588 + 84 = 672
Step 9: 672 + 84 = 756
Step 10: 756 + 84 = 840
Step 11: 840 + 84 = 924
Step 12: 924 + 84 = 1008
Step 13: 1008 + 84 = 1092
Step 14: 1092 + 84 = 1176
Step 15: 1176 + 84 = 1260
Step 16: 1260 + 84 = 1344
Step 17: 1344 + 84 = 1428
Step 18: 1428 + 84 = 1512
Step 19: 1512 + 84 = 1596
Step 20: 1596 + 84 = 1680
Step 21: 1680 + 84 = 1764
Step 22: 1764 + 84 = 1848
Step 23: 1848 + 84 = 1932
Step 24: 1932 + 84 = 2016
Step 25: 2016 + 84 = 2100
Step 26: 2100 + 84 = 2184
Step 27: 2184 + 84 = 2268
Step 28: 2268 + 84 = 2352
Step 29: 2352 + 84 = 2436
Step 30: 2436 + 84 = 2520
Step 31: 2520 + 84 = 2604
Step 32: 2604 + 84 = 2688
Step 33: 2688 + 84 = 2772
Step 34: 2772 + 84 = 2856
Step 35: 2856 + 84 = 2940
Step 36: 2940 + 84 = 3024
Step 37: 3024 + 84 = 3108
Step 38: 3108 + 84 = 3192
Step 39: 3192 + 84 = 3276
Step 40: 3276 + 84 = 3360
Step 41: 3360 + 84 = 3444
Step 42: 3444 + 84 = 3528
Step 43: 3528 + 84 = 3612
Step 44: 3612 + 84 = 3696
Step 45: 3696 + 84 = 3780
Step 46: 3780 + 84 = 3864
Step 47: 3864 + 84 = 3948
Step 48: 3948 + 84 = 4032
Step 49: 4032 + 84 = 4116
Step 50: 4116 + 84 = 4200
Step 51: 4200 + 84 = 4284
Step 52: 4284 + 84 = 4368
Step 53: 4368 + 84 = 4452
Step 54: 4452 + 84 = 4536
Step 55: 4536 + 84 = 4620
Step 56: 4620 + 84 = 4704
Step 57: 4704 + 84 = 4788
Step 58: 4788 + 84 = 4872
Step 59: 4872 + 84 = 4956
Step 60: 4956 + 84 = 5040
Step 61: 5040 + 84 = 5124
Step 62: 5124 + 84 = 5208
Step 63: 5208 + 84 = 5292
Step 64: 5292 + 84 = 5376
Step 65: 5376 + 84 = 5460
Step 66: 5460 + 84 = 5544
Step 67: 5544 + 84 = 5628
Step 68: 5628 + 84 = 5712
Step 69: 5712 + 84 = 5796
Step 70: 5796 + 84 = 5880
Step 71: 5880 + 84 = 5964
Step 72: 5964 + 84 = 6048
Step 73: 6048 + 84 = 6132
Step 74: 6132 + 84 = 6216
Step 75: 6216 + 84 = 6300
Step 76: 6300 + 84 = 6384
Step 77: 6384 + 84 = 6468
Step 78: 6468 + 84 = 6552
Step 79: 6552 + 84 = 6636
Step 80: 6636 + 84 = 6720
Step 81: 6720 + 84 = 6804
Step 82: 6804 + 84 = 6888
Step 83: 6888 + 84 = 6972
Step 84: 6972 + 84 = 7056
Step 85: 7056 + 84 = 7140
Step 86: 7140 + 84 = 7224
Step 87: 7224 + 84 = 7308
Step 88: 7308 + 84 = 7392
Step 89: 7392 + 84 = 7476
Step 90: 7476 + 84 = 7560
Step 91: 7560 + 84 = 7644
Step 92: 7644 + 84 = 7728
Step 93: 7728 + 84 = 7812
Step 94: 7812 + 84 = 7896
Step 95: 7896 + 84 = 7980
Step 96: 7980 + 84 = 8064
Step 97: 8064 + 84 = 8148
Step 98: 8148 + 84 = 8232
Step 99: 8232 + 84 = 8316
Step 100: 8316 + 84 = 8400
Step 101: 8400 + 84 = 8484
Step 102: 8484 + 84 = 8568
Step 103: 8568 + 84 = 8652
Step 104: 8652 + 84 = 8736
Step 105: 8736 + 84 = 8820
Step 106: 8820 + 84 = 8904
Step 107: 8904 + 84 = 8988
Step 108: 8988 + 84 = 9072
Step 109: 9072 + 84 = 9156
Step 110: 9156 + 84 = 9240
Step 111: 9240 + 84 = 9324
Step 112: 9324 + 84 = 9408
Step 113: 9408 + 84 = 9492
Step 114: 9492 + 84 = 9576
Step 115: 9576 + 84 = 9660
Step 116: 9660 + 84 = 9744
Step 117: 9744 + 84 = 9828
Step 118: 9828 + 84 = 9912
Step 119: 9912 + 84 = 9996
Step 120: 9996 + 84 = 10080
Step 121: 10080 + 84 = 10164
Step 122: 10164 + 84 = 10248
Step 123: 10248 + 84 = 10332
Step 124: 10332 + 84 = 10416
Step 125: 10416 + 84 = 10500
Step 126: 10500 + 84 = 10584
Step 127: 10584 + 84 = 10668
Step 128: 10668 + 84 = 10752
Step 129: 10752 + 84 = 10836
Step 130: 10836 + 84 = 10920
Step 131: 10920 + 84 = 11004
Step 132: 11004 + 84 = 11088
Step 133: 11088 + 84 = 11172
Step 134: 11172 + 84 = 11256
Step 135: 11256 + 84 = 11340
Step 136: 11340 + 84 = 11424
Step 137: 11424 + 84 = 11508
Step 138: 11508 + 84 = 11592
Step 139: 11592 + 84 = 11676
Step 140: 11676 + 84 = 11760
Step 141: 11760 + 84 = 11844
Step 142: 11844 + 84 = 11928
Step 143: 11928 + 84 = 12012
Step 144: 12012 + 84 = 12096
Step 145: 12096 + 84 = 12180
Step 146: 12180 + 84 = 12264
Step 147: 12264 + 84 = 12348
Step 148: 12348 + 84 = 12432
Step 149: 12432 + 84 = 12516
Step 150: 12516 + 84 = 12600
Step 151: 12600 + 84 = 12684
Step 152: 12684 + 84 = 12768
Step 153: 12768 + 84 = 12852
Step 154: 12852 + 84 = 12936
Step 155: 12936 + 84 = 13020
Step 156: 13020 + 84 = 13104
Step 157: 13104 + 84 = 13188
Step 158: 13188 + 84 = 13272
Step 159: 13272 + 84 = 13356
Step 160: 13356 + 84 = 13440
Step 161: 13440 + 84 = 13524
Step 162: 13524 + 84 = 13608
Step 163: 13608 + 84 = 13692
Step 164: 13692 + 84 = 13776
Step 165: 13776 + 84 = 13860
Step 166: 13860 + 84 = 13944
Step 167: 13944 + 84 = 14028
Step 168: 14028 + 84 = 14112
Step 169: 14112 + 84 = 14196
Step 170: 14196 + 84 = 14280
Step 171: 14280 + 84 = 14364
Step 172: 14364 + 84 = 14448
Step 173: 14448 + 84 = 14532
Step 174: 14532 + 84 = 14616
Step 175: 14616 + 84 = 14700
Step 176: 14700 + 84 = 14784
Step 177: 14784 + 84 = 14868
Step 178: 14868 + 84 = 14952
Step 179: 14952 + 84 = 15036
Step 180: 15036 + 84 = 15120
Step 181: 15120 + 84 = 15204
Step 182: 15204 + 84 = 15288
Step 183: 15288 + 84 = 15372
Step 184: 15372 + 84 = 15456
Step 185: 15456 + 84 = 15540
Step 186: 15540 + 84 = 15624
Step 187: 15624 + 84 = 15708
Step 188: 15708 + 84 = 15792
Step 189: 15792 + 84 = 15876
Step 190: 15876 + 84 = 15960
Step 191: 15960 + 84 = 16044
Step 192: 16044 + 84 = 16128
Step 193: 16128 + 84 = 16212
Step 194: 16212 + 84 = 16296
Step 195: 16296 + 84 = 16380
Step 196: 16380 + 84 = 16464
Step 197: 16464 + 84 = 16548
Step 198: 16548 + 84 = 16632
Step 199: 16632 + 84 = 16716
Step 200: 16716 + 84 = 16800
Step 201: 16800 + 84 = 16884
Step 202: 16884 + 84 = 16968
Step 203: 16968 + 84 = 17052
Step 204: 17052 + 84 = 17136
Step 205: 17136 + 84 = 17220
Step 206: 17220 + 84 = 17304
Step 207: 17304 + 84 = 17388
Step 208: 17388 + 84 = 17472
Step 209: 17472 + 84 = 17556
Step 210: 17556 + 84 = 17640
Step 211: 17640 + 84 = 17724
Step 212: 17724 + 84 = 17808
Step 213: 17808 + 84 = 17892
Step 214: 17892 + 84 = 17976
Step 215: 17976 + 84 = 18060
Step 216: 18060 + 84 = 18144
Step 217: 18144 + 84 = 18228
Step 218: 18228 + 84 = 18312
Step 219: 18312 + 84 = 18396
Step 220: 18396 + 84 = 18480
Step 221: 18480 + 84 = 18564
Step 222: 18564 + 84 = 18648
Step 223: 18648 + 84 = 18732
Step 224: 18732 + 84 = 18816
Step 225: 18816 + 84 = 18900
Step 226: 18900 + 84 = 18984
Step 227: 18984 + 84 = 19068
Step 228: 19068 + 84 = 19152
Step 229: 19152 + 84 = 19236
Step 230: 19236 + 84 = 19320
Step 231: 19320 + 84 = 19404
Step 232: 19404 + 84 = 19488
Step 233: 19488 + 84 = 19572
Step 234: 19572 + 84 = 19656
Step 235: 19656 + 84 = 19740
Step 236: 19740 + 84 = 19824
Step 237: 19824 + 84 = 19908
Step 238: 19908 + 84 = 19992
Step 239: 19992 + 84 = 20076
Step 240: 20076 + 84 = 20160
Step 241: 20160 + 84 = 20244
Step 242: 20244 + 84 = 20328
Step 243: 20328 + 84 = 20412
Step 244: 20412 + 84 = 20496
Step 245: 20496 + 84 = 20580
Step 246: 20580 + 84 = 20664
Step 247: 20664 + 84 = 20748
Step 248: 20748 + 84 = 20832
Step 249: 20832 + 84 = 20916
Step 250: 20916 + 84 = 21000
Step 251: 21000 + 84 = 21084
Step 252: 21084 + 84 = 21168
Step 253: 21168 + 84 = 21252
Step 254: 21252 + 84 = 21336
Step 255: 21336 + 84 = 21420
Step 256: 21420 + 84 = 21504
Step 257: 21504 + 84 = 21588
Step 258: 21588 + 84 = 21672
Step 259: 21672 + 84 = 21756
Step 260: 21756 + 84 = 21840
Step 261: 21840 + 84 = 21924

So, 84*261 = 21924