Let's get this math done. We have 15 and we're going to multiply it by 353. This is the same as taking 15 and adding it to itself 353 times.
Step 1: 0 + 15 = 15
Step 2: 15 + 15 = 30
Step 3: 30 + 15 = 45
Step 4: 45 + 15 = 60
Step 5: 60 + 15 = 75
Step 6: 75 + 15 = 90
Step 7: 90 + 15 = 105
Step 8: 105 + 15 = 120
Step 9: 120 + 15 = 135
Step 10: 135 + 15 = 150
Step 11: 150 + 15 = 165
Step 12: 165 + 15 = 180
Step 13: 180 + 15 = 195
Step 14: 195 + 15 = 210
Step 15: 210 + 15 = 225
Step 16: 225 + 15 = 240
Step 17: 240 + 15 = 255
Step 18: 255 + 15 = 270
Step 19: 270 + 15 = 285
Step 20: 285 + 15 = 300
Step 21: 300 + 15 = 315
Step 22: 315 + 15 = 330
Step 23: 330 + 15 = 345
Step 24: 345 + 15 = 360
Step 25: 360 + 15 = 375
Step 26: 375 + 15 = 390
Step 27: 390 + 15 = 405
Step 28: 405 + 15 = 420
Step 29: 420 + 15 = 435
Step 30: 435 + 15 = 450
Step 31: 450 + 15 = 465
Step 32: 465 + 15 = 480
Step 33: 480 + 15 = 495
Step 34: 495 + 15 = 510
Step 35: 510 + 15 = 525
Step 36: 525 + 15 = 540
Step 37: 540 + 15 = 555
Step 38: 555 + 15 = 570
Step 39: 570 + 15 = 585
Step 40: 585 + 15 = 600
Step 41: 600 + 15 = 615
Step 42: 615 + 15 = 630
Step 43: 630 + 15 = 645
Step 44: 645 + 15 = 660
Step 45: 660 + 15 = 675
Step 46: 675 + 15 = 690
Step 47: 690 + 15 = 705
Step 48: 705 + 15 = 720
Step 49: 720 + 15 = 735
Step 50: 735 + 15 = 750
Step 51: 750 + 15 = 765
Step 52: 765 + 15 = 780
Step 53: 780 + 15 = 795
Step 54: 795 + 15 = 810
Step 55: 810 + 15 = 825
Step 56: 825 + 15 = 840
Step 57: 840 + 15 = 855
Step 58: 855 + 15 = 870
Step 59: 870 + 15 = 885
Step 60: 885 + 15 = 900
Step 61: 900 + 15 = 915
Step 62: 915 + 15 = 930
Step 63: 930 + 15 = 945
Step 64: 945 + 15 = 960
Step 65: 960 + 15 = 975
Step 66: 975 + 15 = 990
Step 67: 990 + 15 = 1005
Step 68: 1005 + 15 = 1020
Step 69: 1020 + 15 = 1035
Step 70: 1035 + 15 = 1050
Step 71: 1050 + 15 = 1065
Step 72: 1065 + 15 = 1080
Step 73: 1080 + 15 = 1095
Step 74: 1095 + 15 = 1110
Step 75: 1110 + 15 = 1125
Step 76: 1125 + 15 = 1140
Step 77: 1140 + 15 = 1155
Step 78: 1155 + 15 = 1170
Step 79: 1170 + 15 = 1185
Step 80: 1185 + 15 = 1200
Step 81: 1200 + 15 = 1215
Step 82: 1215 + 15 = 1230
Step 83: 1230 + 15 = 1245
Step 84: 1245 + 15 = 1260
Step 85: 1260 + 15 = 1275
Step 86: 1275 + 15 = 1290
Step 87: 1290 + 15 = 1305
Step 88: 1305 + 15 = 1320
Step 89: 1320 + 15 = 1335
Step 90: 1335 + 15 = 1350
Step 91: 1350 + 15 = 1365
Step 92: 1365 + 15 = 1380
Step 93: 1380 + 15 = 1395
Step 94: 1395 + 15 = 1410
Step 95: 1410 + 15 = 1425
Step 96: 1425 + 15 = 1440
Step 97: 1440 + 15 = 1455
Step 98: 1455 + 15 = 1470
Step 99: 1470 + 15 = 1485
Step 100: 1485 + 15 = 1500
Step 101: 1500 + 15 = 1515
Step 102: 1515 + 15 = 1530
Step 103: 1530 + 15 = 1545
Step 104: 1545 + 15 = 1560
Step 105: 1560 + 15 = 1575
Step 106: 1575 + 15 = 1590
Step 107: 1590 + 15 = 1605
Step 108: 1605 + 15 = 1620
Step 109: 1620 + 15 = 1635
Step 110: 1635 + 15 = 1650
Step 111: 1650 + 15 = 1665
Step 112: 1665 + 15 = 1680
Step 113: 1680 + 15 = 1695
Step 114: 1695 + 15 = 1710
Step 115: 1710 + 15 = 1725
Step 116: 1725 + 15 = 1740
Step 117: 1740 + 15 = 1755
Step 118: 1755 + 15 = 1770
Step 119: 1770 + 15 = 1785
Step 120: 1785 + 15 = 1800
Step 121: 1800 + 15 = 1815
Step 122: 1815 + 15 = 1830
Step 123: 1830 + 15 = 1845
Step 124: 1845 + 15 = 1860
Step 125: 1860 + 15 = 1875
Step 126: 1875 + 15 = 1890
Step 127: 1890 + 15 = 1905
Step 128: 1905 + 15 = 1920
Step 129: 1920 + 15 = 1935
Step 130: 1935 + 15 = 1950
Step 131: 1950 + 15 = 1965
Step 132: 1965 + 15 = 1980
Step 133: 1980 + 15 = 1995
Step 134: 1995 + 15 = 2010
Step 135: 2010 + 15 = 2025
Step 136: 2025 + 15 = 2040
Step 137: 2040 + 15 = 2055
Step 138: 2055 + 15 = 2070
Step 139: 2070 + 15 = 2085
Step 140: 2085 + 15 = 2100
Step 141: 2100 + 15 = 2115
Step 142: 2115 + 15 = 2130
Step 143: 2130 + 15 = 2145
Step 144: 2145 + 15 = 2160
Step 145: 2160 + 15 = 2175
Step 146: 2175 + 15 = 2190
Step 147: 2190 + 15 = 2205
Step 148: 2205 + 15 = 2220
Step 149: 2220 + 15 = 2235
Step 150: 2235 + 15 = 2250
Step 151: 2250 + 15 = 2265
Step 152: 2265 + 15 = 2280
Step 153: 2280 + 15 = 2295
Step 154: 2295 + 15 = 2310
Step 155: 2310 + 15 = 2325
Step 156: 2325 + 15 = 2340
Step 157: 2340 + 15 = 2355
Step 158: 2355 + 15 = 2370
Step 159: 2370 + 15 = 2385
Step 160: 2385 + 15 = 2400
Step 161: 2400 + 15 = 2415
Step 162: 2415 + 15 = 2430
Step 163: 2430 + 15 = 2445
Step 164: 2445 + 15 = 2460
Step 165: 2460 + 15 = 2475
Step 166: 2475 + 15 = 2490
Step 167: 2490 + 15 = 2505
Step 168: 2505 + 15 = 2520
Step 169: 2520 + 15 = 2535
Step 170: 2535 + 15 = 2550
Step 171: 2550 + 15 = 2565
Step 172: 2565 + 15 = 2580
Step 173: 2580 + 15 = 2595
Step 174: 2595 + 15 = 2610
Step 175: 2610 + 15 = 2625
Step 176: 2625 + 15 = 2640
Step 177: 2640 + 15 = 2655
Step 178: 2655 + 15 = 2670
Step 179: 2670 + 15 = 2685
Step 180: 2685 + 15 = 2700
Step 181: 2700 + 15 = 2715
Step 182: 2715 + 15 = 2730
Step 183: 2730 + 15 = 2745
Step 184: 2745 + 15 = 2760
Step 185: 2760 + 15 = 2775
Step 186: 2775 + 15 = 2790
Step 187: 2790 + 15 = 2805
Step 188: 2805 + 15 = 2820
Step 189: 2820 + 15 = 2835
Step 190: 2835 + 15 = 2850
Step 191: 2850 + 15 = 2865
Step 192: 2865 + 15 = 2880
Step 193: 2880 + 15 = 2895
Step 194: 2895 + 15 = 2910
Step 195: 2910 + 15 = 2925
Step 196: 2925 + 15 = 2940
Step 197: 2940 + 15 = 2955
Step 198: 2955 + 15 = 2970
Step 199: 2970 + 15 = 2985
Step 200: 2985 + 15 = 3000
Step 201: 3000 + 15 = 3015
Step 202: 3015 + 15 = 3030
Step 203: 3030 + 15 = 3045
Step 204: 3045 + 15 = 3060
Step 205: 3060 + 15 = 3075
Step 206: 3075 + 15 = 3090
Step 207: 3090 + 15 = 3105
Step 208: 3105 + 15 = 3120
Step 209: 3120 + 15 = 3135
Step 210: 3135 + 15 = 3150
Step 211: 3150 + 15 = 3165
Step 212: 3165 + 15 = 3180
Step 213: 3180 + 15 = 3195
Step 214: 3195 + 15 = 3210
Step 215: 3210 + 15 = 3225
Step 216: 3225 + 15 = 3240
Step 217: 3240 + 15 = 3255
Step 218: 3255 + 15 = 3270
Step 219: 3270 + 15 = 3285
Step 220: 3285 + 15 = 3300
Step 221: 3300 + 15 = 3315
Step 222: 3315 + 15 = 3330
Step 223: 3330 + 15 = 3345
Step 224: 3345 + 15 = 3360
Step 225: 3360 + 15 = 3375
Step 226: 3375 + 15 = 3390
Step 227: 3390 + 15 = 3405
Step 228: 3405 + 15 = 3420
Step 229: 3420 + 15 = 3435
Step 230: 3435 + 15 = 3450
Step 231: 3450 + 15 = 3465
Step 232: 3465 + 15 = 3480
Step 233: 3480 + 15 = 3495
Step 234: 3495 + 15 = 3510
Step 235: 3510 + 15 = 3525
Step 236: 3525 + 15 = 3540
Step 237: 3540 + 15 = 3555
Step 238: 3555 + 15 = 3570
Step 239: 3570 + 15 = 3585
Step 240: 3585 + 15 = 3600
Step 241: 3600 + 15 = 3615
Step 242: 3615 + 15 = 3630
Step 243: 3630 + 15 = 3645
Step 244: 3645 + 15 = 3660
Step 245: 3660 + 15 = 3675
Step 246: 3675 + 15 = 3690
Step 247: 3690 + 15 = 3705
Step 248: 3705 + 15 = 3720
Step 249: 3720 + 15 = 3735
Step 250: 3735 + 15 = 3750
Step 251: 3750 + 15 = 3765
Step 252: 3765 + 15 = 3780
Step 253: 3780 + 15 = 3795
Step 254: 3795 + 15 = 3810
Step 255: 3810 + 15 = 3825
Step 256: 3825 + 15 = 3840
Step 257: 3840 + 15 = 3855
Step 258: 3855 + 15 = 3870
Step 259: 3870 + 15 = 3885
Step 260: 3885 + 15 = 3900
Step 261: 3900 + 15 = 3915
Step 262: 3915 + 15 = 3930
Step 263: 3930 + 15 = 3945
Step 264: 3945 + 15 = 3960
Step 265: 3960 + 15 = 3975
Step 266: 3975 + 15 = 3990
Step 267: 3990 + 15 = 4005
Step 268: 4005 + 15 = 4020
Step 269: 4020 + 15 = 4035
Step 270: 4035 + 15 = 4050
Step 271: 4050 + 15 = 4065
Step 272: 4065 + 15 = 4080
Step 273: 4080 + 15 = 4095
Step 274: 4095 + 15 = 4110
Step 275: 4110 + 15 = 4125
Step 276: 4125 + 15 = 4140
Step 277: 4140 + 15 = 4155
Step 278: 4155 + 15 = 4170
Step 279: 4170 + 15 = 4185
Step 280: 4185 + 15 = 4200
Step 281: 4200 + 15 = 4215
Step 282: 4215 + 15 = 4230
Step 283: 4230 + 15 = 4245
Step 284: 4245 + 15 = 4260
Step 285: 4260 + 15 = 4275
Step 286: 4275 + 15 = 4290
Step 287: 4290 + 15 = 4305
Step 288: 4305 + 15 = 4320
Step 289: 4320 + 15 = 4335
Step 290: 4335 + 15 = 4350
Step 291: 4350 + 15 = 4365
Step 292: 4365 + 15 = 4380
Step 293: 4380 + 15 = 4395
Step 294: 4395 + 15 = 4410
Step 295: 4410 + 15 = 4425
Step 296: 4425 + 15 = 4440
Step 297: 4440 + 15 = 4455
Step 298: 4455 + 15 = 4470
Step 299: 4470 + 15 = 4485
Step 300: 4485 + 15 = 4500
Step 301: 4500 + 15 = 4515
Step 302: 4515 + 15 = 4530
Step 303: 4530 + 15 = 4545
Step 304: 4545 + 15 = 4560
Step 305: 4560 + 15 = 4575
Step 306: 4575 + 15 = 4590
Step 307: 4590 + 15 = 4605
Step 308: 4605 + 15 = 4620
Step 309: 4620 + 15 = 4635
Step 310: 4635 + 15 = 4650
Step 311: 4650 + 15 = 4665
Step 312: 4665 + 15 = 4680
Step 313: 4680 + 15 = 4695
Step 314: 4695 + 15 = 4710
Step 315: 4710 + 15 = 4725
Step 316: 4725 + 15 = 4740
Step 317: 4740 + 15 = 4755
Step 318: 4755 + 15 = 4770
Step 319: 4770 + 15 = 4785
Step 320: 4785 + 15 = 4800
Step 321: 4800 + 15 = 4815
Step 322: 4815 + 15 = 4830
Step 323: 4830 + 15 = 4845
Step 324: 4845 + 15 = 4860
Step 325: 4860 + 15 = 4875
Step 326: 4875 + 15 = 4890
Step 327: 4890 + 15 = 4905
Step 328: 4905 + 15 = 4920
Step 329: 4920 + 15 = 4935
Step 330: 4935 + 15 = 4950
Step 331: 4950 + 15 = 4965
Step 332: 4965 + 15 = 4980
Step 333: 4980 + 15 = 4995
Step 334: 4995 + 15 = 5010
Step 335: 5010 + 15 = 5025
Step 336: 5025 + 15 = 5040
Step 337: 5040 + 15 = 5055
Step 338: 5055 + 15 = 5070
Step 339: 5070 + 15 = 5085
Step 340: 5085 + 15 = 5100
Step 341: 5100 + 15 = 5115
Step 342: 5115 + 15 = 5130
Step 343: 5130 + 15 = 5145
Step 344: 5145 + 15 = 5160
Step 345: 5160 + 15 = 5175
Step 346: 5175 + 15 = 5190
Step 347: 5190 + 15 = 5205
Step 348: 5205 + 15 = 5220
Step 349: 5220 + 15 = 5235
Step 350: 5235 + 15 = 5250
Step 351: 5250 + 15 = 5265
Step 352: 5265 + 15 = 5280
Step 353: 5280 + 15 = 5295

So, 15*353 = 5295