OK, let's work through this together. We're starting with 331 and we're going to multiply it by 261, which means we add 331 to itself 261 times.
Step 1: 0 + 331 = 331
Step 2: 331 + 331 = 662
Step 3: 662 + 331 = 993
Step 4: 993 + 331 = 1324
Step 5: 1324 + 331 = 1655
Step 6: 1655 + 331 = 1986
Step 7: 1986 + 331 = 2317
Step 8: 2317 + 331 = 2648
Step 9: 2648 + 331 = 2979
Step 10: 2979 + 331 = 3310
Step 11: 3310 + 331 = 3641
Step 12: 3641 + 331 = 3972
Step 13: 3972 + 331 = 4303
Step 14: 4303 + 331 = 4634
Step 15: 4634 + 331 = 4965
Step 16: 4965 + 331 = 5296
Step 17: 5296 + 331 = 5627
Step 18: 5627 + 331 = 5958
Step 19: 5958 + 331 = 6289
Step 20: 6289 + 331 = 6620
Step 21: 6620 + 331 = 6951
Step 22: 6951 + 331 = 7282
Step 23: 7282 + 331 = 7613
Step 24: 7613 + 331 = 7944
Step 25: 7944 + 331 = 8275
Step 26: 8275 + 331 = 8606
Step 27: 8606 + 331 = 8937
Step 28: 8937 + 331 = 9268
Step 29: 9268 + 331 = 9599
Step 30: 9599 + 331 = 9930
Step 31: 9930 + 331 = 10261
Step 32: 10261 + 331 = 10592
Step 33: 10592 + 331 = 10923
Step 34: 10923 + 331 = 11254
Step 35: 11254 + 331 = 11585
Step 36: 11585 + 331 = 11916
Step 37: 11916 + 331 = 12247
Step 38: 12247 + 331 = 12578
Step 39: 12578 + 331 = 12909
Step 40: 12909 + 331 = 13240
Step 41: 13240 + 331 = 13571
Step 42: 13571 + 331 = 13902
Step 43: 13902 + 331 = 14233
Step 44: 14233 + 331 = 14564
Step 45: 14564 + 331 = 14895
Step 46: 14895 + 331 = 15226
Step 47: 15226 + 331 = 15557
Step 48: 15557 + 331 = 15888
Step 49: 15888 + 331 = 16219
Step 50: 16219 + 331 = 16550
Step 51: 16550 + 331 = 16881
Step 52: 16881 + 331 = 17212
Step 53: 17212 + 331 = 17543
Step 54: 17543 + 331 = 17874
Step 55: 17874 + 331 = 18205
Step 56: 18205 + 331 = 18536
Step 57: 18536 + 331 = 18867
Step 58: 18867 + 331 = 19198
Step 59: 19198 + 331 = 19529
Step 60: 19529 + 331 = 19860
Step 61: 19860 + 331 = 20191
Step 62: 20191 + 331 = 20522
Step 63: 20522 + 331 = 20853
Step 64: 20853 + 331 = 21184
Step 65: 21184 + 331 = 21515
Step 66: 21515 + 331 = 21846
Step 67: 21846 + 331 = 22177
Step 68: 22177 + 331 = 22508
Step 69: 22508 + 331 = 22839
Step 70: 22839 + 331 = 23170
Step 71: 23170 + 331 = 23501
Step 72: 23501 + 331 = 23832
Step 73: 23832 + 331 = 24163
Step 74: 24163 + 331 = 24494
Step 75: 24494 + 331 = 24825
Step 76: 24825 + 331 = 25156
Step 77: 25156 + 331 = 25487
Step 78: 25487 + 331 = 25818
Step 79: 25818 + 331 = 26149
Step 80: 26149 + 331 = 26480
Step 81: 26480 + 331 = 26811
Step 82: 26811 + 331 = 27142
Step 83: 27142 + 331 = 27473
Step 84: 27473 + 331 = 27804
Step 85: 27804 + 331 = 28135
Step 86: 28135 + 331 = 28466
Step 87: 28466 + 331 = 28797
Step 88: 28797 + 331 = 29128
Step 89: 29128 + 331 = 29459
Step 90: 29459 + 331 = 29790
Step 91: 29790 + 331 = 30121
Step 92: 30121 + 331 = 30452
Step 93: 30452 + 331 = 30783
Step 94: 30783 + 331 = 31114
Step 95: 31114 + 331 = 31445
Step 96: 31445 + 331 = 31776
Step 97: 31776 + 331 = 32107
Step 98: 32107 + 331 = 32438
Step 99: 32438 + 331 = 32769
Step 100: 32769 + 331 = 33100
Step 101: 33100 + 331 = 33431
Step 102: 33431 + 331 = 33762
Step 103: 33762 + 331 = 34093
Step 104: 34093 + 331 = 34424
Step 105: 34424 + 331 = 34755
Step 106: 34755 + 331 = 35086
Step 107: 35086 + 331 = 35417
Step 108: 35417 + 331 = 35748
Step 109: 35748 + 331 = 36079
Step 110: 36079 + 331 = 36410
Step 111: 36410 + 331 = 36741
Step 112: 36741 + 331 = 37072
Step 113: 37072 + 331 = 37403
Step 114: 37403 + 331 = 37734
Step 115: 37734 + 331 = 38065
Step 116: 38065 + 331 = 38396
Step 117: 38396 + 331 = 38727
Step 118: 38727 + 331 = 39058
Step 119: 39058 + 331 = 39389
Step 120: 39389 + 331 = 39720
Step 121: 39720 + 331 = 40051
Step 122: 40051 + 331 = 40382
Step 123: 40382 + 331 = 40713
Step 124: 40713 + 331 = 41044
Step 125: 41044 + 331 = 41375
Step 126: 41375 + 331 = 41706
Step 127: 41706 + 331 = 42037
Step 128: 42037 + 331 = 42368
Step 129: 42368 + 331 = 42699
Step 130: 42699 + 331 = 43030
Step 131: 43030 + 331 = 43361
Step 132: 43361 + 331 = 43692
Step 133: 43692 + 331 = 44023
Step 134: 44023 + 331 = 44354
Step 135: 44354 + 331 = 44685
Step 136: 44685 + 331 = 45016
Step 137: 45016 + 331 = 45347
Step 138: 45347 + 331 = 45678
Step 139: 45678 + 331 = 46009
Step 140: 46009 + 331 = 46340
Step 141: 46340 + 331 = 46671
Step 142: 46671 + 331 = 47002
Step 143: 47002 + 331 = 47333
Step 144: 47333 + 331 = 47664
Step 145: 47664 + 331 = 47995
Step 146: 47995 + 331 = 48326
Step 147: 48326 + 331 = 48657
Step 148: 48657 + 331 = 48988
Step 149: 48988 + 331 = 49319
Step 150: 49319 + 331 = 49650
Step 151: 49650 + 331 = 49981
Step 152: 49981 + 331 = 50312
Step 153: 50312 + 331 = 50643
Step 154: 50643 + 331 = 50974
Step 155: 50974 + 331 = 51305
Step 156: 51305 + 331 = 51636
Step 157: 51636 + 331 = 51967
Step 158: 51967 + 331 = 52298
Step 159: 52298 + 331 = 52629
Step 160: 52629 + 331 = 52960
Step 161: 52960 + 331 = 53291
Step 162: 53291 + 331 = 53622
Step 163: 53622 + 331 = 53953
Step 164: 53953 + 331 = 54284
Step 165: 54284 + 331 = 54615
Step 166: 54615 + 331 = 54946
Step 167: 54946 + 331 = 55277
Step 168: 55277 + 331 = 55608
Step 169: 55608 + 331 = 55939
Step 170: 55939 + 331 = 56270
Step 171: 56270 + 331 = 56601
Step 172: 56601 + 331 = 56932
Step 173: 56932 + 331 = 57263
Step 174: 57263 + 331 = 57594
Step 175: 57594 + 331 = 57925
Step 176: 57925 + 331 = 58256
Step 177: 58256 + 331 = 58587
Step 178: 58587 + 331 = 58918
Step 179: 58918 + 331 = 59249
Step 180: 59249 + 331 = 59580
Step 181: 59580 + 331 = 59911
Step 182: 59911 + 331 = 60242
Step 183: 60242 + 331 = 60573
Step 184: 60573 + 331 = 60904
Step 185: 60904 + 331 = 61235
Step 186: 61235 + 331 = 61566
Step 187: 61566 + 331 = 61897
Step 188: 61897 + 331 = 62228
Step 189: 62228 + 331 = 62559
Step 190: 62559 + 331 = 62890
Step 191: 62890 + 331 = 63221
Step 192: 63221 + 331 = 63552
Step 193: 63552 + 331 = 63883
Step 194: 63883 + 331 = 64214
Step 195: 64214 + 331 = 64545
Step 196: 64545 + 331 = 64876
Step 197: 64876 + 331 = 65207
Step 198: 65207 + 331 = 65538
Step 199: 65538 + 331 = 65869
Step 200: 65869 + 331 = 66200
Step 201: 66200 + 331 = 66531
Step 202: 66531 + 331 = 66862
Step 203: 66862 + 331 = 67193
Step 204: 67193 + 331 = 67524
Step 205: 67524 + 331 = 67855
Step 206: 67855 + 331 = 68186
Step 207: 68186 + 331 = 68517
Step 208: 68517 + 331 = 68848
Step 209: 68848 + 331 = 69179
Step 210: 69179 + 331 = 69510
Step 211: 69510 + 331 = 69841
Step 212: 69841 + 331 = 70172
Step 213: 70172 + 331 = 70503
Step 214: 70503 + 331 = 70834
Step 215: 70834 + 331 = 71165
Step 216: 71165 + 331 = 71496
Step 217: 71496 + 331 = 71827
Step 218: 71827 + 331 = 72158
Step 219: 72158 + 331 = 72489
Step 220: 72489 + 331 = 72820
Step 221: 72820 + 331 = 73151
Step 222: 73151 + 331 = 73482
Step 223: 73482 + 331 = 73813
Step 224: 73813 + 331 = 74144
Step 225: 74144 + 331 = 74475
Step 226: 74475 + 331 = 74806
Step 227: 74806 + 331 = 75137
Step 228: 75137 + 331 = 75468
Step 229: 75468 + 331 = 75799
Step 230: 75799 + 331 = 76130
Step 231: 76130 + 331 = 76461
Step 232: 76461 + 331 = 76792
Step 233: 76792 + 331 = 77123
Step 234: 77123 + 331 = 77454
Step 235: 77454 + 331 = 77785
Step 236: 77785 + 331 = 78116
Step 237: 78116 + 331 = 78447
Step 238: 78447 + 331 = 78778
Step 239: 78778 + 331 = 79109
Step 240: 79109 + 331 = 79440
Step 241: 79440 + 331 = 79771
Step 242: 79771 + 331 = 80102
Step 243: 80102 + 331 = 80433
Step 244: 80433 + 331 = 80764
Step 245: 80764 + 331 = 81095
Step 246: 81095 + 331 = 81426
Step 247: 81426 + 331 = 81757
Step 248: 81757 + 331 = 82088
Step 249: 82088 + 331 = 82419
Step 250: 82419 + 331 = 82750
Step 251: 82750 + 331 = 83081
Step 252: 83081 + 331 = 83412
Step 253: 83412 + 331 = 83743
Step 254: 83743 + 331 = 84074
Step 255: 84074 + 331 = 84405
Step 256: 84405 + 331 = 84736
Step 257: 84736 + 331 = 85067
Step 258: 85067 + 331 = 85398
Step 259: 85398 + 331 = 85729
Step 260: 85729 + 331 = 86060
Step 261: 86060 + 331 = 86391

So, 331*261 = 86391