OK, let's crack this. We're given 810 and our task is to multiply it by 313. Essentially, we'll be adding 810 to itself 313 times.
Step 1: 0 + 810 = 810
Step 2: 810 + 810 = 1620
Step 3: 1620 + 810 = 2430
Step 4: 2430 + 810 = 3240
Step 5: 3240 + 810 = 4050
Step 6: 4050 + 810 = 4860
Step 7: 4860 + 810 = 5670
Step 8: 5670 + 810 = 6480
Step 9: 6480 + 810 = 7290
Step 10: 7290 + 810 = 8100
Step 11: 8100 + 810 = 8910
Step 12: 8910 + 810 = 9720
Step 13: 9720 + 810 = 10530
Step 14: 10530 + 810 = 11340
Step 15: 11340 + 810 = 12150
Step 16: 12150 + 810 = 12960
Step 17: 12960 + 810 = 13770
Step 18: 13770 + 810 = 14580
Step 19: 14580 + 810 = 15390
Step 20: 15390 + 810 = 16200
Step 21: 16200 + 810 = 17010
Step 22: 17010 + 810 = 17820
Step 23: 17820 + 810 = 18630
Step 24: 18630 + 810 = 19440
Step 25: 19440 + 810 = 20250
Step 26: 20250 + 810 = 21060
Step 27: 21060 + 810 = 21870
Step 28: 21870 + 810 = 22680
Step 29: 22680 + 810 = 23490
Step 30: 23490 + 810 = 24300
Step 31: 24300 + 810 = 25110
Step 32: 25110 + 810 = 25920
Step 33: 25920 + 810 = 26730
Step 34: 26730 + 810 = 27540
Step 35: 27540 + 810 = 28350
Step 36: 28350 + 810 = 29160
Step 37: 29160 + 810 = 29970
Step 38: 29970 + 810 = 30780
Step 39: 30780 + 810 = 31590
Step 40: 31590 + 810 = 32400
Step 41: 32400 + 810 = 33210
Step 42: 33210 + 810 = 34020
Step 43: 34020 + 810 = 34830
Step 44: 34830 + 810 = 35640
Step 45: 35640 + 810 = 36450
Step 46: 36450 + 810 = 37260
Step 47: 37260 + 810 = 38070
Step 48: 38070 + 810 = 38880
Step 49: 38880 + 810 = 39690
Step 50: 39690 + 810 = 40500
Step 51: 40500 + 810 = 41310
Step 52: 41310 + 810 = 42120
Step 53: 42120 + 810 = 42930
Step 54: 42930 + 810 = 43740
Step 55: 43740 + 810 = 44550
Step 56: 44550 + 810 = 45360
Step 57: 45360 + 810 = 46170
Step 58: 46170 + 810 = 46980
Step 59: 46980 + 810 = 47790
Step 60: 47790 + 810 = 48600
Step 61: 48600 + 810 = 49410
Step 62: 49410 + 810 = 50220
Step 63: 50220 + 810 = 51030
Step 64: 51030 + 810 = 51840
Step 65: 51840 + 810 = 52650
Step 66: 52650 + 810 = 53460
Step 67: 53460 + 810 = 54270
Step 68: 54270 + 810 = 55080
Step 69: 55080 + 810 = 55890
Step 70: 55890 + 810 = 56700
Step 71: 56700 + 810 = 57510
Step 72: 57510 + 810 = 58320
Step 73: 58320 + 810 = 59130
Step 74: 59130 + 810 = 59940
Step 75: 59940 + 810 = 60750
Step 76: 60750 + 810 = 61560
Step 77: 61560 + 810 = 62370
Step 78: 62370 + 810 = 63180
Step 79: 63180 + 810 = 63990
Step 80: 63990 + 810 = 64800
Step 81: 64800 + 810 = 65610
Step 82: 65610 + 810 = 66420
Step 83: 66420 + 810 = 67230
Step 84: 67230 + 810 = 68040
Step 85: 68040 + 810 = 68850
Step 86: 68850 + 810 = 69660
Step 87: 69660 + 810 = 70470
Step 88: 70470 + 810 = 71280
Step 89: 71280 + 810 = 72090
Step 90: 72090 + 810 = 72900
Step 91: 72900 + 810 = 73710
Step 92: 73710 + 810 = 74520
Step 93: 74520 + 810 = 75330
Step 94: 75330 + 810 = 76140
Step 95: 76140 + 810 = 76950
Step 96: 76950 + 810 = 77760
Step 97: 77760 + 810 = 78570
Step 98: 78570 + 810 = 79380
Step 99: 79380 + 810 = 80190
Step 100: 80190 + 810 = 81000
Step 101: 81000 + 810 = 81810
Step 102: 81810 + 810 = 82620
Step 103: 82620 + 810 = 83430
Step 104: 83430 + 810 = 84240
Step 105: 84240 + 810 = 85050
Step 106: 85050 + 810 = 85860
Step 107: 85860 + 810 = 86670
Step 108: 86670 + 810 = 87480
Step 109: 87480 + 810 = 88290
Step 110: 88290 + 810 = 89100
Step 111: 89100 + 810 = 89910
Step 112: 89910 + 810 = 90720
Step 113: 90720 + 810 = 91530
Step 114: 91530 + 810 = 92340
Step 115: 92340 + 810 = 93150
Step 116: 93150 + 810 = 93960
Step 117: 93960 + 810 = 94770
Step 118: 94770 + 810 = 95580
Step 119: 95580 + 810 = 96390
Step 120: 96390 + 810 = 97200
Step 121: 97200 + 810 = 98010
Step 122: 98010 + 810 = 98820
Step 123: 98820 + 810 = 99630
Step 124: 99630 + 810 = 100440
Step 125: 100440 + 810 = 101250
Step 126: 101250 + 810 = 102060
Step 127: 102060 + 810 = 102870
Step 128: 102870 + 810 = 103680
Step 129: 103680 + 810 = 104490
Step 130: 104490 + 810 = 105300
Step 131: 105300 + 810 = 106110
Step 132: 106110 + 810 = 106920
Step 133: 106920 + 810 = 107730
Step 134: 107730 + 810 = 108540
Step 135: 108540 + 810 = 109350
Step 136: 109350 + 810 = 110160
Step 137: 110160 + 810 = 110970
Step 138: 110970 + 810 = 111780
Step 139: 111780 + 810 = 112590
Step 140: 112590 + 810 = 113400
Step 141: 113400 + 810 = 114210
Step 142: 114210 + 810 = 115020
Step 143: 115020 + 810 = 115830
Step 144: 115830 + 810 = 116640
Step 145: 116640 + 810 = 117450
Step 146: 117450 + 810 = 118260
Step 147: 118260 + 810 = 119070
Step 148: 119070 + 810 = 119880
Step 149: 119880 + 810 = 120690
Step 150: 120690 + 810 = 121500
Step 151: 121500 + 810 = 122310
Step 152: 122310 + 810 = 123120
Step 153: 123120 + 810 = 123930
Step 154: 123930 + 810 = 124740
Step 155: 124740 + 810 = 125550
Step 156: 125550 + 810 = 126360
Step 157: 126360 + 810 = 127170
Step 158: 127170 + 810 = 127980
Step 159: 127980 + 810 = 128790
Step 160: 128790 + 810 = 129600
Step 161: 129600 + 810 = 130410
Step 162: 130410 + 810 = 131220
Step 163: 131220 + 810 = 132030
Step 164: 132030 + 810 = 132840
Step 165: 132840 + 810 = 133650
Step 166: 133650 + 810 = 134460
Step 167: 134460 + 810 = 135270
Step 168: 135270 + 810 = 136080
Step 169: 136080 + 810 = 136890
Step 170: 136890 + 810 = 137700
Step 171: 137700 + 810 = 138510
Step 172: 138510 + 810 = 139320
Step 173: 139320 + 810 = 140130
Step 174: 140130 + 810 = 140940
Step 175: 140940 + 810 = 141750
Step 176: 141750 + 810 = 142560
Step 177: 142560 + 810 = 143370
Step 178: 143370 + 810 = 144180
Step 179: 144180 + 810 = 144990
Step 180: 144990 + 810 = 145800
Step 181: 145800 + 810 = 146610
Step 182: 146610 + 810 = 147420
Step 183: 147420 + 810 = 148230
Step 184: 148230 + 810 = 149040
Step 185: 149040 + 810 = 149850
Step 186: 149850 + 810 = 150660
Step 187: 150660 + 810 = 151470
Step 188: 151470 + 810 = 152280
Step 189: 152280 + 810 = 153090
Step 190: 153090 + 810 = 153900
Step 191: 153900 + 810 = 154710
Step 192: 154710 + 810 = 155520
Step 193: 155520 + 810 = 156330
Step 194: 156330 + 810 = 157140
Step 195: 157140 + 810 = 157950
Step 196: 157950 + 810 = 158760
Step 197: 158760 + 810 = 159570
Step 198: 159570 + 810 = 160380
Step 199: 160380 + 810 = 161190
Step 200: 161190 + 810 = 162000
Step 201: 162000 + 810 = 162810
Step 202: 162810 + 810 = 163620
Step 203: 163620 + 810 = 164430
Step 204: 164430 + 810 = 165240
Step 205: 165240 + 810 = 166050
Step 206: 166050 + 810 = 166860
Step 207: 166860 + 810 = 167670
Step 208: 167670 + 810 = 168480
Step 209: 168480 + 810 = 169290
Step 210: 169290 + 810 = 170100
Step 211: 170100 + 810 = 170910
Step 212: 170910 + 810 = 171720
Step 213: 171720 + 810 = 172530
Step 214: 172530 + 810 = 173340
Step 215: 173340 + 810 = 174150
Step 216: 174150 + 810 = 174960
Step 217: 174960 + 810 = 175770
Step 218: 175770 + 810 = 176580
Step 219: 176580 + 810 = 177390
Step 220: 177390 + 810 = 178200
Step 221: 178200 + 810 = 179010
Step 222: 179010 + 810 = 179820
Step 223: 179820 + 810 = 180630
Step 224: 180630 + 810 = 181440
Step 225: 181440 + 810 = 182250
Step 226: 182250 + 810 = 183060
Step 227: 183060 + 810 = 183870
Step 228: 183870 + 810 = 184680
Step 229: 184680 + 810 = 185490
Step 230: 185490 + 810 = 186300
Step 231: 186300 + 810 = 187110
Step 232: 187110 + 810 = 187920
Step 233: 187920 + 810 = 188730
Step 234: 188730 + 810 = 189540
Step 235: 189540 + 810 = 190350
Step 236: 190350 + 810 = 191160
Step 237: 191160 + 810 = 191970
Step 238: 191970 + 810 = 192780
Step 239: 192780 + 810 = 193590
Step 240: 193590 + 810 = 194400
Step 241: 194400 + 810 = 195210
Step 242: 195210 + 810 = 196020
Step 243: 196020 + 810 = 196830
Step 244: 196830 + 810 = 197640
Step 245: 197640 + 810 = 198450
Step 246: 198450 + 810 = 199260
Step 247: 199260 + 810 = 200070
Step 248: 200070 + 810 = 200880
Step 249: 200880 + 810 = 201690
Step 250: 201690 + 810 = 202500
Step 251: 202500 + 810 = 203310
Step 252: 203310 + 810 = 204120
Step 253: 204120 + 810 = 204930
Step 254: 204930 + 810 = 205740
Step 255: 205740 + 810 = 206550
Step 256: 206550 + 810 = 207360
Step 257: 207360 + 810 = 208170
Step 258: 208170 + 810 = 208980
Step 259: 208980 + 810 = 209790
Step 260: 209790 + 810 = 210600
Step 261: 210600 + 810 = 211410
Step 262: 211410 + 810 = 212220
Step 263: 212220 + 810 = 213030
Step 264: 213030 + 810 = 213840
Step 265: 213840 + 810 = 214650
Step 266: 214650 + 810 = 215460
Step 267: 215460 + 810 = 216270
Step 268: 216270 + 810 = 217080
Step 269: 217080 + 810 = 217890
Step 270: 217890 + 810 = 218700
Step 271: 218700 + 810 = 219510
Step 272: 219510 + 810 = 220320
Step 273: 220320 + 810 = 221130
Step 274: 221130 + 810 = 221940
Step 275: 221940 + 810 = 222750
Step 276: 222750 + 810 = 223560
Step 277: 223560 + 810 = 224370
Step 278: 224370 + 810 = 225180
Step 279: 225180 + 810 = 225990
Step 280: 225990 + 810 = 226800
Step 281: 226800 + 810 = 227610
Step 282: 227610 + 810 = 228420
Step 283: 228420 + 810 = 229230
Step 284: 229230 + 810 = 230040
Step 285: 230040 + 810 = 230850
Step 286: 230850 + 810 = 231660
Step 287: 231660 + 810 = 232470
Step 288: 232470 + 810 = 233280
Step 289: 233280 + 810 = 234090
Step 290: 234090 + 810 = 234900
Step 291: 234900 + 810 = 235710
Step 292: 235710 + 810 = 236520
Step 293: 236520 + 810 = 237330
Step 294: 237330 + 810 = 238140
Step 295: 238140 + 810 = 238950
Step 296: 238950 + 810 = 239760
Step 297: 239760 + 810 = 240570
Step 298: 240570 + 810 = 241380
Step 299: 241380 + 810 = 242190
Step 300: 242190 + 810 = 243000
Step 301: 243000 + 810 = 243810
Step 302: 243810 + 810 = 244620
Step 303: 244620 + 810 = 245430
Step 304: 245430 + 810 = 246240
Step 305: 246240 + 810 = 247050
Step 306: 247050 + 810 = 247860
Step 307: 247860 + 810 = 248670
Step 308: 248670 + 810 = 249480
Step 309: 249480 + 810 = 250290
Step 310: 250290 + 810 = 251100
Step 311: 251100 + 810 = 251910
Step 312: 251910 + 810 = 252720
Step 313: 252720 + 810 = 253530

So, 810*313 = 253530