Let's roll up our sleeves and solve this. We have 90 and we're going to multiply it by 453, essentially adding 90 to itself 453 times.
Step 1: 0 + 90 = 90
Step 2: 90 + 90 = 180
Step 3: 180 + 90 = 270
Step 4: 270 + 90 = 360
Step 5: 360 + 90 = 450
Step 6: 450 + 90 = 540
Step 7: 540 + 90 = 630
Step 8: 630 + 90 = 720
Step 9: 720 + 90 = 810
Step 10: 810 + 90 = 900
Step 11: 900 + 90 = 990
Step 12: 990 + 90 = 1080
Step 13: 1080 + 90 = 1170
Step 14: 1170 + 90 = 1260
Step 15: 1260 + 90 = 1350
Step 16: 1350 + 90 = 1440
Step 17: 1440 + 90 = 1530
Step 18: 1530 + 90 = 1620
Step 19: 1620 + 90 = 1710
Step 20: 1710 + 90 = 1800
Step 21: 1800 + 90 = 1890
Step 22: 1890 + 90 = 1980
Step 23: 1980 + 90 = 2070
Step 24: 2070 + 90 = 2160
Step 25: 2160 + 90 = 2250
Step 26: 2250 + 90 = 2340
Step 27: 2340 + 90 = 2430
Step 28: 2430 + 90 = 2520
Step 29: 2520 + 90 = 2610
Step 30: 2610 + 90 = 2700
Step 31: 2700 + 90 = 2790
Step 32: 2790 + 90 = 2880
Step 33: 2880 + 90 = 2970
Step 34: 2970 + 90 = 3060
Step 35: 3060 + 90 = 3150
Step 36: 3150 + 90 = 3240
Step 37: 3240 + 90 = 3330
Step 38: 3330 + 90 = 3420
Step 39: 3420 + 90 = 3510
Step 40: 3510 + 90 = 3600
Step 41: 3600 + 90 = 3690
Step 42: 3690 + 90 = 3780
Step 43: 3780 + 90 = 3870
Step 44: 3870 + 90 = 3960
Step 45: 3960 + 90 = 4050
Step 46: 4050 + 90 = 4140
Step 47: 4140 + 90 = 4230
Step 48: 4230 + 90 = 4320
Step 49: 4320 + 90 = 4410
Step 50: 4410 + 90 = 4500
Step 51: 4500 + 90 = 4590
Step 52: 4590 + 90 = 4680
Step 53: 4680 + 90 = 4770
Step 54: 4770 + 90 = 4860
Step 55: 4860 + 90 = 4950
Step 56: 4950 + 90 = 5040
Step 57: 5040 + 90 = 5130
Step 58: 5130 + 90 = 5220
Step 59: 5220 + 90 = 5310
Step 60: 5310 + 90 = 5400
Step 61: 5400 + 90 = 5490
Step 62: 5490 + 90 = 5580
Step 63: 5580 + 90 = 5670
Step 64: 5670 + 90 = 5760
Step 65: 5760 + 90 = 5850
Step 66: 5850 + 90 = 5940
Step 67: 5940 + 90 = 6030
Step 68: 6030 + 90 = 6120
Step 69: 6120 + 90 = 6210
Step 70: 6210 + 90 = 6300
Step 71: 6300 + 90 = 6390
Step 72: 6390 + 90 = 6480
Step 73: 6480 + 90 = 6570
Step 74: 6570 + 90 = 6660
Step 75: 6660 + 90 = 6750
Step 76: 6750 + 90 = 6840
Step 77: 6840 + 90 = 6930
Step 78: 6930 + 90 = 7020
Step 79: 7020 + 90 = 7110
Step 80: 7110 + 90 = 7200
Step 81: 7200 + 90 = 7290
Step 82: 7290 + 90 = 7380
Step 83: 7380 + 90 = 7470
Step 84: 7470 + 90 = 7560
Step 85: 7560 + 90 = 7650
Step 86: 7650 + 90 = 7740
Step 87: 7740 + 90 = 7830
Step 88: 7830 + 90 = 7920
Step 89: 7920 + 90 = 8010
Step 90: 8010 + 90 = 8100
Step 91: 8100 + 90 = 8190
Step 92: 8190 + 90 = 8280
Step 93: 8280 + 90 = 8370
Step 94: 8370 + 90 = 8460
Step 95: 8460 + 90 = 8550
Step 96: 8550 + 90 = 8640
Step 97: 8640 + 90 = 8730
Step 98: 8730 + 90 = 8820
Step 99: 8820 + 90 = 8910
Step 100: 8910 + 90 = 9000
Step 101: 9000 + 90 = 9090
Step 102: 9090 + 90 = 9180
Step 103: 9180 + 90 = 9270
Step 104: 9270 + 90 = 9360
Step 105: 9360 + 90 = 9450
Step 106: 9450 + 90 = 9540
Step 107: 9540 + 90 = 9630
Step 108: 9630 + 90 = 9720
Step 109: 9720 + 90 = 9810
Step 110: 9810 + 90 = 9900
Step 111: 9900 + 90 = 9990
Step 112: 9990 + 90 = 10080
Step 113: 10080 + 90 = 10170
Step 114: 10170 + 90 = 10260
Step 115: 10260 + 90 = 10350
Step 116: 10350 + 90 = 10440
Step 117: 10440 + 90 = 10530
Step 118: 10530 + 90 = 10620
Step 119: 10620 + 90 = 10710
Step 120: 10710 + 90 = 10800
Step 121: 10800 + 90 = 10890
Step 122: 10890 + 90 = 10980
Step 123: 10980 + 90 = 11070
Step 124: 11070 + 90 = 11160
Step 125: 11160 + 90 = 11250
Step 126: 11250 + 90 = 11340
Step 127: 11340 + 90 = 11430
Step 128: 11430 + 90 = 11520
Step 129: 11520 + 90 = 11610
Step 130: 11610 + 90 = 11700
Step 131: 11700 + 90 = 11790
Step 132: 11790 + 90 = 11880
Step 133: 11880 + 90 = 11970
Step 134: 11970 + 90 = 12060
Step 135: 12060 + 90 = 12150
Step 136: 12150 + 90 = 12240
Step 137: 12240 + 90 = 12330
Step 138: 12330 + 90 = 12420
Step 139: 12420 + 90 = 12510
Step 140: 12510 + 90 = 12600
Step 141: 12600 + 90 = 12690
Step 142: 12690 + 90 = 12780
Step 143: 12780 + 90 = 12870
Step 144: 12870 + 90 = 12960
Step 145: 12960 + 90 = 13050
Step 146: 13050 + 90 = 13140
Step 147: 13140 + 90 = 13230
Step 148: 13230 + 90 = 13320
Step 149: 13320 + 90 = 13410
Step 150: 13410 + 90 = 13500
Step 151: 13500 + 90 = 13590
Step 152: 13590 + 90 = 13680
Step 153: 13680 + 90 = 13770
Step 154: 13770 + 90 = 13860
Step 155: 13860 + 90 = 13950
Step 156: 13950 + 90 = 14040
Step 157: 14040 + 90 = 14130
Step 158: 14130 + 90 = 14220
Step 159: 14220 + 90 = 14310
Step 160: 14310 + 90 = 14400
Step 161: 14400 + 90 = 14490
Step 162: 14490 + 90 = 14580
Step 163: 14580 + 90 = 14670
Step 164: 14670 + 90 = 14760
Step 165: 14760 + 90 = 14850
Step 166: 14850 + 90 = 14940
Step 167: 14940 + 90 = 15030
Step 168: 15030 + 90 = 15120
Step 169: 15120 + 90 = 15210
Step 170: 15210 + 90 = 15300
Step 171: 15300 + 90 = 15390
Step 172: 15390 + 90 = 15480
Step 173: 15480 + 90 = 15570
Step 174: 15570 + 90 = 15660
Step 175: 15660 + 90 = 15750
Step 176: 15750 + 90 = 15840
Step 177: 15840 + 90 = 15930
Step 178: 15930 + 90 = 16020
Step 179: 16020 + 90 = 16110
Step 180: 16110 + 90 = 16200
Step 181: 16200 + 90 = 16290
Step 182: 16290 + 90 = 16380
Step 183: 16380 + 90 = 16470
Step 184: 16470 + 90 = 16560
Step 185: 16560 + 90 = 16650
Step 186: 16650 + 90 = 16740
Step 187: 16740 + 90 = 16830
Step 188: 16830 + 90 = 16920
Step 189: 16920 + 90 = 17010
Step 190: 17010 + 90 = 17100
Step 191: 17100 + 90 = 17190
Step 192: 17190 + 90 = 17280
Step 193: 17280 + 90 = 17370
Step 194: 17370 + 90 = 17460
Step 195: 17460 + 90 = 17550
Step 196: 17550 + 90 = 17640
Step 197: 17640 + 90 = 17730
Step 198: 17730 + 90 = 17820
Step 199: 17820 + 90 = 17910
Step 200: 17910 + 90 = 18000
Step 201: 18000 + 90 = 18090
Step 202: 18090 + 90 = 18180
Step 203: 18180 + 90 = 18270
Step 204: 18270 + 90 = 18360
Step 205: 18360 + 90 = 18450
Step 206: 18450 + 90 = 18540
Step 207: 18540 + 90 = 18630
Step 208: 18630 + 90 = 18720
Step 209: 18720 + 90 = 18810
Step 210: 18810 + 90 = 18900
Step 211: 18900 + 90 = 18990
Step 212: 18990 + 90 = 19080
Step 213: 19080 + 90 = 19170
Step 214: 19170 + 90 = 19260
Step 215: 19260 + 90 = 19350
Step 216: 19350 + 90 = 19440
Step 217: 19440 + 90 = 19530
Step 218: 19530 + 90 = 19620
Step 219: 19620 + 90 = 19710
Step 220: 19710 + 90 = 19800
Step 221: 19800 + 90 = 19890
Step 222: 19890 + 90 = 19980
Step 223: 19980 + 90 = 20070
Step 224: 20070 + 90 = 20160
Step 225: 20160 + 90 = 20250
Step 226: 20250 + 90 = 20340
Step 227: 20340 + 90 = 20430
Step 228: 20430 + 90 = 20520
Step 229: 20520 + 90 = 20610
Step 230: 20610 + 90 = 20700
Step 231: 20700 + 90 = 20790
Step 232: 20790 + 90 = 20880
Step 233: 20880 + 90 = 20970
Step 234: 20970 + 90 = 21060
Step 235: 21060 + 90 = 21150
Step 236: 21150 + 90 = 21240
Step 237: 21240 + 90 = 21330
Step 238: 21330 + 90 = 21420
Step 239: 21420 + 90 = 21510
Step 240: 21510 + 90 = 21600
Step 241: 21600 + 90 = 21690
Step 242: 21690 + 90 = 21780
Step 243: 21780 + 90 = 21870
Step 244: 21870 + 90 = 21960
Step 245: 21960 + 90 = 22050
Step 246: 22050 + 90 = 22140
Step 247: 22140 + 90 = 22230
Step 248: 22230 + 90 = 22320
Step 249: 22320 + 90 = 22410
Step 250: 22410 + 90 = 22500
Step 251: 22500 + 90 = 22590
Step 252: 22590 + 90 = 22680
Step 253: 22680 + 90 = 22770
Step 254: 22770 + 90 = 22860
Step 255: 22860 + 90 = 22950
Step 256: 22950 + 90 = 23040
Step 257: 23040 + 90 = 23130
Step 258: 23130 + 90 = 23220
Step 259: 23220 + 90 = 23310
Step 260: 23310 + 90 = 23400
Step 261: 23400 + 90 = 23490
Step 262: 23490 + 90 = 23580
Step 263: 23580 + 90 = 23670
Step 264: 23670 + 90 = 23760
Step 265: 23760 + 90 = 23850
Step 266: 23850 + 90 = 23940
Step 267: 23940 + 90 = 24030
Step 268: 24030 + 90 = 24120
Step 269: 24120 + 90 = 24210
Step 270: 24210 + 90 = 24300
Step 271: 24300 + 90 = 24390
Step 272: 24390 + 90 = 24480
Step 273: 24480 + 90 = 24570
Step 274: 24570 + 90 = 24660
Step 275: 24660 + 90 = 24750
Step 276: 24750 + 90 = 24840
Step 277: 24840 + 90 = 24930
Step 278: 24930 + 90 = 25020
Step 279: 25020 + 90 = 25110
Step 280: 25110 + 90 = 25200
Step 281: 25200 + 90 = 25290
Step 282: 25290 + 90 = 25380
Step 283: 25380 + 90 = 25470
Step 284: 25470 + 90 = 25560
Step 285: 25560 + 90 = 25650
Step 286: 25650 + 90 = 25740
Step 287: 25740 + 90 = 25830
Step 288: 25830 + 90 = 25920
Step 289: 25920 + 90 = 26010
Step 290: 26010 + 90 = 26100
Step 291: 26100 + 90 = 26190
Step 292: 26190 + 90 = 26280
Step 293: 26280 + 90 = 26370
Step 294: 26370 + 90 = 26460
Step 295: 26460 + 90 = 26550
Step 296: 26550 + 90 = 26640
Step 297: 26640 + 90 = 26730
Step 298: 26730 + 90 = 26820
Step 299: 26820 + 90 = 26910
Step 300: 26910 + 90 = 27000
Step 301: 27000 + 90 = 27090
Step 302: 27090 + 90 = 27180
Step 303: 27180 + 90 = 27270
Step 304: 27270 + 90 = 27360
Step 305: 27360 + 90 = 27450
Step 306: 27450 + 90 = 27540
Step 307: 27540 + 90 = 27630
Step 308: 27630 + 90 = 27720
Step 309: 27720 + 90 = 27810
Step 310: 27810 + 90 = 27900
Step 311: 27900 + 90 = 27990
Step 312: 27990 + 90 = 28080
Step 313: 28080 + 90 = 28170
Step 314: 28170 + 90 = 28260
Step 315: 28260 + 90 = 28350
Step 316: 28350 + 90 = 28440
Step 317: 28440 + 90 = 28530
Step 318: 28530 + 90 = 28620
Step 319: 28620 + 90 = 28710
Step 320: 28710 + 90 = 28800
Step 321: 28800 + 90 = 28890
Step 322: 28890 + 90 = 28980
Step 323: 28980 + 90 = 29070
Step 324: 29070 + 90 = 29160
Step 325: 29160 + 90 = 29250
Step 326: 29250 + 90 = 29340
Step 327: 29340 + 90 = 29430
Step 328: 29430 + 90 = 29520
Step 329: 29520 + 90 = 29610
Step 330: 29610 + 90 = 29700
Step 331: 29700 + 90 = 29790
Step 332: 29790 + 90 = 29880
Step 333: 29880 + 90 = 29970
Step 334: 29970 + 90 = 30060
Step 335: 30060 + 90 = 30150
Step 336: 30150 + 90 = 30240
Step 337: 30240 + 90 = 30330
Step 338: 30330 + 90 = 30420
Step 339: 30420 + 90 = 30510
Step 340: 30510 + 90 = 30600
Step 341: 30600 + 90 = 30690
Step 342: 30690 + 90 = 30780
Step 343: 30780 + 90 = 30870
Step 344: 30870 + 90 = 30960
Step 345: 30960 + 90 = 31050
Step 346: 31050 + 90 = 31140
Step 347: 31140 + 90 = 31230
Step 348: 31230 + 90 = 31320
Step 349: 31320 + 90 = 31410
Step 350: 31410 + 90 = 31500
Step 351: 31500 + 90 = 31590
Step 352: 31590 + 90 = 31680
Step 353: 31680 + 90 = 31770
Step 354: 31770 + 90 = 31860
Step 355: 31860 + 90 = 31950
Step 356: 31950 + 90 = 32040
Step 357: 32040 + 90 = 32130
Step 358: 32130 + 90 = 32220
Step 359: 32220 + 90 = 32310
Step 360: 32310 + 90 = 32400
Step 361: 32400 + 90 = 32490
Step 362: 32490 + 90 = 32580
Step 363: 32580 + 90 = 32670
Step 364: 32670 + 90 = 32760
Step 365: 32760 + 90 = 32850
Step 366: 32850 + 90 = 32940
Step 367: 32940 + 90 = 33030
Step 368: 33030 + 90 = 33120
Step 369: 33120 + 90 = 33210
Step 370: 33210 + 90 = 33300
Step 371: 33300 + 90 = 33390
Step 372: 33390 + 90 = 33480
Step 373: 33480 + 90 = 33570
Step 374: 33570 + 90 = 33660
Step 375: 33660 + 90 = 33750
Step 376: 33750 + 90 = 33840
Step 377: 33840 + 90 = 33930
Step 378: 33930 + 90 = 34020
Step 379: 34020 + 90 = 34110
Step 380: 34110 + 90 = 34200
Step 381: 34200 + 90 = 34290
Step 382: 34290 + 90 = 34380
Step 383: 34380 + 90 = 34470
Step 384: 34470 + 90 = 34560
Step 385: 34560 + 90 = 34650
Step 386: 34650 + 90 = 34740
Step 387: 34740 + 90 = 34830
Step 388: 34830 + 90 = 34920
Step 389: 34920 + 90 = 35010
Step 390: 35010 + 90 = 35100
Step 391: 35100 + 90 = 35190
Step 392: 35190 + 90 = 35280
Step 393: 35280 + 90 = 35370
Step 394: 35370 + 90 = 35460
Step 395: 35460 + 90 = 35550
Step 396: 35550 + 90 = 35640
Step 397: 35640 + 90 = 35730
Step 398: 35730 + 90 = 35820
Step 399: 35820 + 90 = 35910
Step 400: 35910 + 90 = 36000
Step 401: 36000 + 90 = 36090
Step 402: 36090 + 90 = 36180
Step 403: 36180 + 90 = 36270
Step 404: 36270 + 90 = 36360
Step 405: 36360 + 90 = 36450
Step 406: 36450 + 90 = 36540
Step 407: 36540 + 90 = 36630
Step 408: 36630 + 90 = 36720
Step 409: 36720 + 90 = 36810
Step 410: 36810 + 90 = 36900
Step 411: 36900 + 90 = 36990
Step 412: 36990 + 90 = 37080
Step 413: 37080 + 90 = 37170
Step 414: 37170 + 90 = 37260
Step 415: 37260 + 90 = 37350
Step 416: 37350 + 90 = 37440
Step 417: 37440 + 90 = 37530
Step 418: 37530 + 90 = 37620
Step 419: 37620 + 90 = 37710
Step 420: 37710 + 90 = 37800
Step 421: 37800 + 90 = 37890
Step 422: 37890 + 90 = 37980
Step 423: 37980 + 90 = 38070
Step 424: 38070 + 90 = 38160
Step 425: 38160 + 90 = 38250
Step 426: 38250 + 90 = 38340
Step 427: 38340 + 90 = 38430
Step 428: 38430 + 90 = 38520
Step 429: 38520 + 90 = 38610
Step 430: 38610 + 90 = 38700
Step 431: 38700 + 90 = 38790
Step 432: 38790 + 90 = 38880
Step 433: 38880 + 90 = 38970
Step 434: 38970 + 90 = 39060
Step 435: 39060 + 90 = 39150
Step 436: 39150 + 90 = 39240
Step 437: 39240 + 90 = 39330
Step 438: 39330 + 90 = 39420
Step 439: 39420 + 90 = 39510
Step 440: 39510 + 90 = 39600
Step 441: 39600 + 90 = 39690
Step 442: 39690 + 90 = 39780
Step 443: 39780 + 90 = 39870
Step 444: 39870 + 90 = 39960
Step 445: 39960 + 90 = 40050
Step 446: 40050 + 90 = 40140
Step 447: 40140 + 90 = 40230
Step 448: 40230 + 90 = 40320
Step 449: 40320 + 90 = 40410
Step 450: 40410 + 90 = 40500
Step 451: 40500 + 90 = 40590
Step 452: 40590 + 90 = 40680
Step 453: 40680 + 90 = 40770

So, 90*453 = 40770