Without delay, let's solve this. We've got 259 and we will be multiplying it by 90, that is, adding 259 to itself 90 times.
Step 1: 0 + 259 = 259
Step 2: 259 + 259 = 518
Step 3: 518 + 259 = 777
Step 4: 777 + 259 = 1036
Step 5: 1036 + 259 = 1295
Step 6: 1295 + 259 = 1554
Step 7: 1554 + 259 = 1813
Step 8: 1813 + 259 = 2072
Step 9: 2072 + 259 = 2331
Step 10: 2331 + 259 = 2590
Step 11: 2590 + 259 = 2849
Step 12: 2849 + 259 = 3108
Step 13: 3108 + 259 = 3367
Step 14: 3367 + 259 = 3626
Step 15: 3626 + 259 = 3885
Step 16: 3885 + 259 = 4144
Step 17: 4144 + 259 = 4403
Step 18: 4403 + 259 = 4662
Step 19: 4662 + 259 = 4921
Step 20: 4921 + 259 = 5180
Step 21: 5180 + 259 = 5439
Step 22: 5439 + 259 = 5698
Step 23: 5698 + 259 = 5957
Step 24: 5957 + 259 = 6216
Step 25: 6216 + 259 = 6475
Step 26: 6475 + 259 = 6734
Step 27: 6734 + 259 = 6993
Step 28: 6993 + 259 = 7252
Step 29: 7252 + 259 = 7511
Step 30: 7511 + 259 = 7770
Step 31: 7770 + 259 = 8029
Step 32: 8029 + 259 = 8288
Step 33: 8288 + 259 = 8547
Step 34: 8547 + 259 = 8806
Step 35: 8806 + 259 = 9065
Step 36: 9065 + 259 = 9324
Step 37: 9324 + 259 = 9583
Step 38: 9583 + 259 = 9842
Step 39: 9842 + 259 = 10101
Step 40: 10101 + 259 = 10360
Step 41: 10360 + 259 = 10619
Step 42: 10619 + 259 = 10878
Step 43: 10878 + 259 = 11137
Step 44: 11137 + 259 = 11396
Step 45: 11396 + 259 = 11655
Step 46: 11655 + 259 = 11914
Step 47: 11914 + 259 = 12173
Step 48: 12173 + 259 = 12432
Step 49: 12432 + 259 = 12691
Step 50: 12691 + 259 = 12950
Step 51: 12950 + 259 = 13209
Step 52: 13209 + 259 = 13468
Step 53: 13468 + 259 = 13727
Step 54: 13727 + 259 = 13986
Step 55: 13986 + 259 = 14245
Step 56: 14245 + 259 = 14504
Step 57: 14504 + 259 = 14763
Step 58: 14763 + 259 = 15022
Step 59: 15022 + 259 = 15281
Step 60: 15281 + 259 = 15540
Step 61: 15540 + 259 = 15799
Step 62: 15799 + 259 = 16058
Step 63: 16058 + 259 = 16317
Step 64: 16317 + 259 = 16576
Step 65: 16576 + 259 = 16835
Step 66: 16835 + 259 = 17094
Step 67: 17094 + 259 = 17353
Step 68: 17353 + 259 = 17612
Step 69: 17612 + 259 = 17871
Step 70: 17871 + 259 = 18130
Step 71: 18130 + 259 = 18389
Step 72: 18389 + 259 = 18648
Step 73: 18648 + 259 = 18907
Step 74: 18907 + 259 = 19166
Step 75: 19166 + 259 = 19425
Step 76: 19425 + 259 = 19684
Step 77: 19684 + 259 = 19943
Step 78: 19943 + 259 = 20202
Step 79: 20202 + 259 = 20461
Step 80: 20461 + 259 = 20720
Step 81: 20720 + 259 = 20979
Step 82: 20979 + 259 = 21238
Step 83: 21238 + 259 = 21497
Step 84: 21497 + 259 = 21756
Step 85: 21756 + 259 = 22015
Step 86: 22015 + 259 = 22274
Step 87: 22274 + 259 = 22533
Step 88: 22533 + 259 = 22792
Step 89: 22792 + 259 = 23051
Step 90: 23051 + 259 = 23310

So, 259*90 = 23310