OK, let's work through this together. We're starting with 78 and we're going to multiply it by 121, which means we add 78 to itself 121 times.
Step 1: 0 + 78 = 78
Step 2: 78 + 78 = 156
Step 3: 156 + 78 = 234
Step 4: 234 + 78 = 312
Step 5: 312 + 78 = 390
Step 6: 390 + 78 = 468
Step 7: 468 + 78 = 546
Step 8: 546 + 78 = 624
Step 9: 624 + 78 = 702
Step 10: 702 + 78 = 780
Step 11: 780 + 78 = 858
Step 12: 858 + 78 = 936
Step 13: 936 + 78 = 1014
Step 14: 1014 + 78 = 1092
Step 15: 1092 + 78 = 1170
Step 16: 1170 + 78 = 1248
Step 17: 1248 + 78 = 1326
Step 18: 1326 + 78 = 1404
Step 19: 1404 + 78 = 1482
Step 20: 1482 + 78 = 1560
Step 21: 1560 + 78 = 1638
Step 22: 1638 + 78 = 1716
Step 23: 1716 + 78 = 1794
Step 24: 1794 + 78 = 1872
Step 25: 1872 + 78 = 1950
Step 26: 1950 + 78 = 2028
Step 27: 2028 + 78 = 2106
Step 28: 2106 + 78 = 2184
Step 29: 2184 + 78 = 2262
Step 30: 2262 + 78 = 2340
Step 31: 2340 + 78 = 2418
Step 32: 2418 + 78 = 2496
Step 33: 2496 + 78 = 2574
Step 34: 2574 + 78 = 2652
Step 35: 2652 + 78 = 2730
Step 36: 2730 + 78 = 2808
Step 37: 2808 + 78 = 2886
Step 38: 2886 + 78 = 2964
Step 39: 2964 + 78 = 3042
Step 40: 3042 + 78 = 3120
Step 41: 3120 + 78 = 3198
Step 42: 3198 + 78 = 3276
Step 43: 3276 + 78 = 3354
Step 44: 3354 + 78 = 3432
Step 45: 3432 + 78 = 3510
Step 46: 3510 + 78 = 3588
Step 47: 3588 + 78 = 3666
Step 48: 3666 + 78 = 3744
Step 49: 3744 + 78 = 3822
Step 50: 3822 + 78 = 3900
Step 51: 3900 + 78 = 3978
Step 52: 3978 + 78 = 4056
Step 53: 4056 + 78 = 4134
Step 54: 4134 + 78 = 4212
Step 55: 4212 + 78 = 4290
Step 56: 4290 + 78 = 4368
Step 57: 4368 + 78 = 4446
Step 58: 4446 + 78 = 4524
Step 59: 4524 + 78 = 4602
Step 60: 4602 + 78 = 4680
Step 61: 4680 + 78 = 4758
Step 62: 4758 + 78 = 4836
Step 63: 4836 + 78 = 4914
Step 64: 4914 + 78 = 4992
Step 65: 4992 + 78 = 5070
Step 66: 5070 + 78 = 5148
Step 67: 5148 + 78 = 5226
Step 68: 5226 + 78 = 5304
Step 69: 5304 + 78 = 5382
Step 70: 5382 + 78 = 5460
Step 71: 5460 + 78 = 5538
Step 72: 5538 + 78 = 5616
Step 73: 5616 + 78 = 5694
Step 74: 5694 + 78 = 5772
Step 75: 5772 + 78 = 5850
Step 76: 5850 + 78 = 5928
Step 77: 5928 + 78 = 6006
Step 78: 6006 + 78 = 6084
Step 79: 6084 + 78 = 6162
Step 80: 6162 + 78 = 6240
Step 81: 6240 + 78 = 6318
Step 82: 6318 + 78 = 6396
Step 83: 6396 + 78 = 6474
Step 84: 6474 + 78 = 6552
Step 85: 6552 + 78 = 6630
Step 86: 6630 + 78 = 6708
Step 87: 6708 + 78 = 6786
Step 88: 6786 + 78 = 6864
Step 89: 6864 + 78 = 6942
Step 90: 6942 + 78 = 7020
Step 91: 7020 + 78 = 7098
Step 92: 7098 + 78 = 7176
Step 93: 7176 + 78 = 7254
Step 94: 7254 + 78 = 7332
Step 95: 7332 + 78 = 7410
Step 96: 7410 + 78 = 7488
Step 97: 7488 + 78 = 7566
Step 98: 7566 + 78 = 7644
Step 99: 7644 + 78 = 7722
Step 100: 7722 + 78 = 7800
Step 101: 7800 + 78 = 7878
Step 102: 7878 + 78 = 7956
Step 103: 7956 + 78 = 8034
Step 104: 8034 + 78 = 8112
Step 105: 8112 + 78 = 8190
Step 106: 8190 + 78 = 8268
Step 107: 8268 + 78 = 8346
Step 108: 8346 + 78 = 8424
Step 109: 8424 + 78 = 8502
Step 110: 8502 + 78 = 8580
Step 111: 8580 + 78 = 8658
Step 112: 8658 + 78 = 8736
Step 113: 8736 + 78 = 8814
Step 114: 8814 + 78 = 8892
Step 115: 8892 + 78 = 8970
Step 116: 8970 + 78 = 9048
Step 117: 9048 + 78 = 9126
Step 118: 9126 + 78 = 9204
Step 119: 9204 + 78 = 9282
Step 120: 9282 + 78 = 9360
Step 121: 9360 + 78 = 9438

So, 78*121 = 9438