Without delay, let's solve this. We've got 39 and we will be multiplying it by 400, that is, adding 39 to itself 400 times.
Step 1: 0 + 39 = 39
Step 2: 39 + 39 = 78
Step 3: 78 + 39 = 117
Step 4: 117 + 39 = 156
Step 5: 156 + 39 = 195
Step 6: 195 + 39 = 234
Step 7: 234 + 39 = 273
Step 8: 273 + 39 = 312
Step 9: 312 + 39 = 351
Step 10: 351 + 39 = 390
Step 11: 390 + 39 = 429
Step 12: 429 + 39 = 468
Step 13: 468 + 39 = 507
Step 14: 507 + 39 = 546
Step 15: 546 + 39 = 585
Step 16: 585 + 39 = 624
Step 17: 624 + 39 = 663
Step 18: 663 + 39 = 702
Step 19: 702 + 39 = 741
Step 20: 741 + 39 = 780
Step 21: 780 + 39 = 819
Step 22: 819 + 39 = 858
Step 23: 858 + 39 = 897
Step 24: 897 + 39 = 936
Step 25: 936 + 39 = 975
Step 26: 975 + 39 = 1014
Step 27: 1014 + 39 = 1053
Step 28: 1053 + 39 = 1092
Step 29: 1092 + 39 = 1131
Step 30: 1131 + 39 = 1170
Step 31: 1170 + 39 = 1209
Step 32: 1209 + 39 = 1248
Step 33: 1248 + 39 = 1287
Step 34: 1287 + 39 = 1326
Step 35: 1326 + 39 = 1365
Step 36: 1365 + 39 = 1404
Step 37: 1404 + 39 = 1443
Step 38: 1443 + 39 = 1482
Step 39: 1482 + 39 = 1521
Step 40: 1521 + 39 = 1560
Step 41: 1560 + 39 = 1599
Step 42: 1599 + 39 = 1638
Step 43: 1638 + 39 = 1677
Step 44: 1677 + 39 = 1716
Step 45: 1716 + 39 = 1755
Step 46: 1755 + 39 = 1794
Step 47: 1794 + 39 = 1833
Step 48: 1833 + 39 = 1872
Step 49: 1872 + 39 = 1911
Step 50: 1911 + 39 = 1950
Step 51: 1950 + 39 = 1989
Step 52: 1989 + 39 = 2028
Step 53: 2028 + 39 = 2067
Step 54: 2067 + 39 = 2106
Step 55: 2106 + 39 = 2145
Step 56: 2145 + 39 = 2184
Step 57: 2184 + 39 = 2223
Step 58: 2223 + 39 = 2262
Step 59: 2262 + 39 = 2301
Step 60: 2301 + 39 = 2340
Step 61: 2340 + 39 = 2379
Step 62: 2379 + 39 = 2418
Step 63: 2418 + 39 = 2457
Step 64: 2457 + 39 = 2496
Step 65: 2496 + 39 = 2535
Step 66: 2535 + 39 = 2574
Step 67: 2574 + 39 = 2613
Step 68: 2613 + 39 = 2652
Step 69: 2652 + 39 = 2691
Step 70: 2691 + 39 = 2730
Step 71: 2730 + 39 = 2769
Step 72: 2769 + 39 = 2808
Step 73: 2808 + 39 = 2847
Step 74: 2847 + 39 = 2886
Step 75: 2886 + 39 = 2925
Step 76: 2925 + 39 = 2964
Step 77: 2964 + 39 = 3003
Step 78: 3003 + 39 = 3042
Step 79: 3042 + 39 = 3081
Step 80: 3081 + 39 = 3120
Step 81: 3120 + 39 = 3159
Step 82: 3159 + 39 = 3198
Step 83: 3198 + 39 = 3237
Step 84: 3237 + 39 = 3276
Step 85: 3276 + 39 = 3315
Step 86: 3315 + 39 = 3354
Step 87: 3354 + 39 = 3393
Step 88: 3393 + 39 = 3432
Step 89: 3432 + 39 = 3471
Step 90: 3471 + 39 = 3510
Step 91: 3510 + 39 = 3549
Step 92: 3549 + 39 = 3588
Step 93: 3588 + 39 = 3627
Step 94: 3627 + 39 = 3666
Step 95: 3666 + 39 = 3705
Step 96: 3705 + 39 = 3744
Step 97: 3744 + 39 = 3783
Step 98: 3783 + 39 = 3822
Step 99: 3822 + 39 = 3861
Step 100: 3861 + 39 = 3900
Step 101: 3900 + 39 = 3939
Step 102: 3939 + 39 = 3978
Step 103: 3978 + 39 = 4017
Step 104: 4017 + 39 = 4056
Step 105: 4056 + 39 = 4095
Step 106: 4095 + 39 = 4134
Step 107: 4134 + 39 = 4173
Step 108: 4173 + 39 = 4212
Step 109: 4212 + 39 = 4251
Step 110: 4251 + 39 = 4290
Step 111: 4290 + 39 = 4329
Step 112: 4329 + 39 = 4368
Step 113: 4368 + 39 = 4407
Step 114: 4407 + 39 = 4446
Step 115: 4446 + 39 = 4485
Step 116: 4485 + 39 = 4524
Step 117: 4524 + 39 = 4563
Step 118: 4563 + 39 = 4602
Step 119: 4602 + 39 = 4641
Step 120: 4641 + 39 = 4680
Step 121: 4680 + 39 = 4719
Step 122: 4719 + 39 = 4758
Step 123: 4758 + 39 = 4797
Step 124: 4797 + 39 = 4836
Step 125: 4836 + 39 = 4875
Step 126: 4875 + 39 = 4914
Step 127: 4914 + 39 = 4953
Step 128: 4953 + 39 = 4992
Step 129: 4992 + 39 = 5031
Step 130: 5031 + 39 = 5070
Step 131: 5070 + 39 = 5109
Step 132: 5109 + 39 = 5148
Step 133: 5148 + 39 = 5187
Step 134: 5187 + 39 = 5226
Step 135: 5226 + 39 = 5265
Step 136: 5265 + 39 = 5304
Step 137: 5304 + 39 = 5343
Step 138: 5343 + 39 = 5382
Step 139: 5382 + 39 = 5421
Step 140: 5421 + 39 = 5460
Step 141: 5460 + 39 = 5499
Step 142: 5499 + 39 = 5538
Step 143: 5538 + 39 = 5577
Step 144: 5577 + 39 = 5616
Step 145: 5616 + 39 = 5655
Step 146: 5655 + 39 = 5694
Step 147: 5694 + 39 = 5733
Step 148: 5733 + 39 = 5772
Step 149: 5772 + 39 = 5811
Step 150: 5811 + 39 = 5850
Step 151: 5850 + 39 = 5889
Step 152: 5889 + 39 = 5928
Step 153: 5928 + 39 = 5967
Step 154: 5967 + 39 = 6006
Step 155: 6006 + 39 = 6045
Step 156: 6045 + 39 = 6084
Step 157: 6084 + 39 = 6123
Step 158: 6123 + 39 = 6162
Step 159: 6162 + 39 = 6201
Step 160: 6201 + 39 = 6240
Step 161: 6240 + 39 = 6279
Step 162: 6279 + 39 = 6318
Step 163: 6318 + 39 = 6357
Step 164: 6357 + 39 = 6396
Step 165: 6396 + 39 = 6435
Step 166: 6435 + 39 = 6474
Step 167: 6474 + 39 = 6513
Step 168: 6513 + 39 = 6552
Step 169: 6552 + 39 = 6591
Step 170: 6591 + 39 = 6630
Step 171: 6630 + 39 = 6669
Step 172: 6669 + 39 = 6708
Step 173: 6708 + 39 = 6747
Step 174: 6747 + 39 = 6786
Step 175: 6786 + 39 = 6825
Step 176: 6825 + 39 = 6864
Step 177: 6864 + 39 = 6903
Step 178: 6903 + 39 = 6942
Step 179: 6942 + 39 = 6981
Step 180: 6981 + 39 = 7020
Step 181: 7020 + 39 = 7059
Step 182: 7059 + 39 = 7098
Step 183: 7098 + 39 = 7137
Step 184: 7137 + 39 = 7176
Step 185: 7176 + 39 = 7215
Step 186: 7215 + 39 = 7254
Step 187: 7254 + 39 = 7293
Step 188: 7293 + 39 = 7332
Step 189: 7332 + 39 = 7371
Step 190: 7371 + 39 = 7410
Step 191: 7410 + 39 = 7449
Step 192: 7449 + 39 = 7488
Step 193: 7488 + 39 = 7527
Step 194: 7527 + 39 = 7566
Step 195: 7566 + 39 = 7605
Step 196: 7605 + 39 = 7644
Step 197: 7644 + 39 = 7683
Step 198: 7683 + 39 = 7722
Step 199: 7722 + 39 = 7761
Step 200: 7761 + 39 = 7800
Step 201: 7800 + 39 = 7839
Step 202: 7839 + 39 = 7878
Step 203: 7878 + 39 = 7917
Step 204: 7917 + 39 = 7956
Step 205: 7956 + 39 = 7995
Step 206: 7995 + 39 = 8034
Step 207: 8034 + 39 = 8073
Step 208: 8073 + 39 = 8112
Step 209: 8112 + 39 = 8151
Step 210: 8151 + 39 = 8190
Step 211: 8190 + 39 = 8229
Step 212: 8229 + 39 = 8268
Step 213: 8268 + 39 = 8307
Step 214: 8307 + 39 = 8346
Step 215: 8346 + 39 = 8385
Step 216: 8385 + 39 = 8424
Step 217: 8424 + 39 = 8463
Step 218: 8463 + 39 = 8502
Step 219: 8502 + 39 = 8541
Step 220: 8541 + 39 = 8580
Step 221: 8580 + 39 = 8619
Step 222: 8619 + 39 = 8658
Step 223: 8658 + 39 = 8697
Step 224: 8697 + 39 = 8736
Step 225: 8736 + 39 = 8775
Step 226: 8775 + 39 = 8814
Step 227: 8814 + 39 = 8853
Step 228: 8853 + 39 = 8892
Step 229: 8892 + 39 = 8931
Step 230: 8931 + 39 = 8970
Step 231: 8970 + 39 = 9009
Step 232: 9009 + 39 = 9048
Step 233: 9048 + 39 = 9087
Step 234: 9087 + 39 = 9126
Step 235: 9126 + 39 = 9165
Step 236: 9165 + 39 = 9204
Step 237: 9204 + 39 = 9243
Step 238: 9243 + 39 = 9282
Step 239: 9282 + 39 = 9321
Step 240: 9321 + 39 = 9360
Step 241: 9360 + 39 = 9399
Step 242: 9399 + 39 = 9438
Step 243: 9438 + 39 = 9477
Step 244: 9477 + 39 = 9516
Step 245: 9516 + 39 = 9555
Step 246: 9555 + 39 = 9594
Step 247: 9594 + 39 = 9633
Step 248: 9633 + 39 = 9672
Step 249: 9672 + 39 = 9711
Step 250: 9711 + 39 = 9750
Step 251: 9750 + 39 = 9789
Step 252: 9789 + 39 = 9828
Step 253: 9828 + 39 = 9867
Step 254: 9867 + 39 = 9906
Step 255: 9906 + 39 = 9945
Step 256: 9945 + 39 = 9984
Step 257: 9984 + 39 = 10023
Step 258: 10023 + 39 = 10062
Step 259: 10062 + 39 = 10101
Step 260: 10101 + 39 = 10140
Step 261: 10140 + 39 = 10179
Step 262: 10179 + 39 = 10218
Step 263: 10218 + 39 = 10257
Step 264: 10257 + 39 = 10296
Step 265: 10296 + 39 = 10335
Step 266: 10335 + 39 = 10374
Step 267: 10374 + 39 = 10413
Step 268: 10413 + 39 = 10452
Step 269: 10452 + 39 = 10491
Step 270: 10491 + 39 = 10530
Step 271: 10530 + 39 = 10569
Step 272: 10569 + 39 = 10608
Step 273: 10608 + 39 = 10647
Step 274: 10647 + 39 = 10686
Step 275: 10686 + 39 = 10725
Step 276: 10725 + 39 = 10764
Step 277: 10764 + 39 = 10803
Step 278: 10803 + 39 = 10842
Step 279: 10842 + 39 = 10881
Step 280: 10881 + 39 = 10920
Step 281: 10920 + 39 = 10959
Step 282: 10959 + 39 = 10998
Step 283: 10998 + 39 = 11037
Step 284: 11037 + 39 = 11076
Step 285: 11076 + 39 = 11115
Step 286: 11115 + 39 = 11154
Step 287: 11154 + 39 = 11193
Step 288: 11193 + 39 = 11232
Step 289: 11232 + 39 = 11271
Step 290: 11271 + 39 = 11310
Step 291: 11310 + 39 = 11349
Step 292: 11349 + 39 = 11388
Step 293: 11388 + 39 = 11427
Step 294: 11427 + 39 = 11466
Step 295: 11466 + 39 = 11505
Step 296: 11505 + 39 = 11544
Step 297: 11544 + 39 = 11583
Step 298: 11583 + 39 = 11622
Step 299: 11622 + 39 = 11661
Step 300: 11661 + 39 = 11700
Step 301: 11700 + 39 = 11739
Step 302: 11739 + 39 = 11778
Step 303: 11778 + 39 = 11817
Step 304: 11817 + 39 = 11856
Step 305: 11856 + 39 = 11895
Step 306: 11895 + 39 = 11934
Step 307: 11934 + 39 = 11973
Step 308: 11973 + 39 = 12012
Step 309: 12012 + 39 = 12051
Step 310: 12051 + 39 = 12090
Step 311: 12090 + 39 = 12129
Step 312: 12129 + 39 = 12168
Step 313: 12168 + 39 = 12207
Step 314: 12207 + 39 = 12246
Step 315: 12246 + 39 = 12285
Step 316: 12285 + 39 = 12324
Step 317: 12324 + 39 = 12363
Step 318: 12363 + 39 = 12402
Step 319: 12402 + 39 = 12441
Step 320: 12441 + 39 = 12480
Step 321: 12480 + 39 = 12519
Step 322: 12519 + 39 = 12558
Step 323: 12558 + 39 = 12597
Step 324: 12597 + 39 = 12636
Step 325: 12636 + 39 = 12675
Step 326: 12675 + 39 = 12714
Step 327: 12714 + 39 = 12753
Step 328: 12753 + 39 = 12792
Step 329: 12792 + 39 = 12831
Step 330: 12831 + 39 = 12870
Step 331: 12870 + 39 = 12909
Step 332: 12909 + 39 = 12948
Step 333: 12948 + 39 = 12987
Step 334: 12987 + 39 = 13026
Step 335: 13026 + 39 = 13065
Step 336: 13065 + 39 = 13104
Step 337: 13104 + 39 = 13143
Step 338: 13143 + 39 = 13182
Step 339: 13182 + 39 = 13221
Step 340: 13221 + 39 = 13260
Step 341: 13260 + 39 = 13299
Step 342: 13299 + 39 = 13338
Step 343: 13338 + 39 = 13377
Step 344: 13377 + 39 = 13416
Step 345: 13416 + 39 = 13455
Step 346: 13455 + 39 = 13494
Step 347: 13494 + 39 = 13533
Step 348: 13533 + 39 = 13572
Step 349: 13572 + 39 = 13611
Step 350: 13611 + 39 = 13650
Step 351: 13650 + 39 = 13689
Step 352: 13689 + 39 = 13728
Step 353: 13728 + 39 = 13767
Step 354: 13767 + 39 = 13806
Step 355: 13806 + 39 = 13845
Step 356: 13845 + 39 = 13884
Step 357: 13884 + 39 = 13923
Step 358: 13923 + 39 = 13962
Step 359: 13962 + 39 = 14001
Step 360: 14001 + 39 = 14040
Step 361: 14040 + 39 = 14079
Step 362: 14079 + 39 = 14118
Step 363: 14118 + 39 = 14157
Step 364: 14157 + 39 = 14196
Step 365: 14196 + 39 = 14235
Step 366: 14235 + 39 = 14274
Step 367: 14274 + 39 = 14313
Step 368: 14313 + 39 = 14352
Step 369: 14352 + 39 = 14391
Step 370: 14391 + 39 = 14430
Step 371: 14430 + 39 = 14469
Step 372: 14469 + 39 = 14508
Step 373: 14508 + 39 = 14547
Step 374: 14547 + 39 = 14586
Step 375: 14586 + 39 = 14625
Step 376: 14625 + 39 = 14664
Step 377: 14664 + 39 = 14703
Step 378: 14703 + 39 = 14742
Step 379: 14742 + 39 = 14781
Step 380: 14781 + 39 = 14820
Step 381: 14820 + 39 = 14859
Step 382: 14859 + 39 = 14898
Step 383: 14898 + 39 = 14937
Step 384: 14937 + 39 = 14976
Step 385: 14976 + 39 = 15015
Step 386: 15015 + 39 = 15054
Step 387: 15054 + 39 = 15093
Step 388: 15093 + 39 = 15132
Step 389: 15132 + 39 = 15171
Step 390: 15171 + 39 = 15210
Step 391: 15210 + 39 = 15249
Step 392: 15249 + 39 = 15288
Step 393: 15288 + 39 = 15327
Step 394: 15327 + 39 = 15366
Step 395: 15366 + 39 = 15405
Step 396: 15405 + 39 = 15444
Step 397: 15444 + 39 = 15483
Step 398: 15483 + 39 = 15522
Step 399: 15522 + 39 = 15561
Step 400: 15561 + 39 = 15600

So, 39*400 = 15600