Let's get this math done. We have 784 and we're going to multiply it by 99. This is the same as taking 784 and adding it to itself 99 times.
Step 1: 0 + 784 = 784
Step 2: 784 + 784 = 1568
Step 3: 1568 + 784 = 2352
Step 4: 2352 + 784 = 3136
Step 5: 3136 + 784 = 3920
Step 6: 3920 + 784 = 4704
Step 7: 4704 + 784 = 5488
Step 8: 5488 + 784 = 6272
Step 9: 6272 + 784 = 7056
Step 10: 7056 + 784 = 7840
Step 11: 7840 + 784 = 8624
Step 12: 8624 + 784 = 9408
Step 13: 9408 + 784 = 10192
Step 14: 10192 + 784 = 10976
Step 15: 10976 + 784 = 11760
Step 16: 11760 + 784 = 12544
Step 17: 12544 + 784 = 13328
Step 18: 13328 + 784 = 14112
Step 19: 14112 + 784 = 14896
Step 20: 14896 + 784 = 15680
Step 21: 15680 + 784 = 16464
Step 22: 16464 + 784 = 17248
Step 23: 17248 + 784 = 18032
Step 24: 18032 + 784 = 18816
Step 25: 18816 + 784 = 19600
Step 26: 19600 + 784 = 20384
Step 27: 20384 + 784 = 21168
Step 28: 21168 + 784 = 21952
Step 29: 21952 + 784 = 22736
Step 30: 22736 + 784 = 23520
Step 31: 23520 + 784 = 24304
Step 32: 24304 + 784 = 25088
Step 33: 25088 + 784 = 25872
Step 34: 25872 + 784 = 26656
Step 35: 26656 + 784 = 27440
Step 36: 27440 + 784 = 28224
Step 37: 28224 + 784 = 29008
Step 38: 29008 + 784 = 29792
Step 39: 29792 + 784 = 30576
Step 40: 30576 + 784 = 31360
Step 41: 31360 + 784 = 32144
Step 42: 32144 + 784 = 32928
Step 43: 32928 + 784 = 33712
Step 44: 33712 + 784 = 34496
Step 45: 34496 + 784 = 35280
Step 46: 35280 + 784 = 36064
Step 47: 36064 + 784 = 36848
Step 48: 36848 + 784 = 37632
Step 49: 37632 + 784 = 38416
Step 50: 38416 + 784 = 39200
Step 51: 39200 + 784 = 39984
Step 52: 39984 + 784 = 40768
Step 53: 40768 + 784 = 41552
Step 54: 41552 + 784 = 42336
Step 55: 42336 + 784 = 43120
Step 56: 43120 + 784 = 43904
Step 57: 43904 + 784 = 44688
Step 58: 44688 + 784 = 45472
Step 59: 45472 + 784 = 46256
Step 60: 46256 + 784 = 47040
Step 61: 47040 + 784 = 47824
Step 62: 47824 + 784 = 48608
Step 63: 48608 + 784 = 49392
Step 64: 49392 + 784 = 50176
Step 65: 50176 + 784 = 50960
Step 66: 50960 + 784 = 51744
Step 67: 51744 + 784 = 52528
Step 68: 52528 + 784 = 53312
Step 69: 53312 + 784 = 54096
Step 70: 54096 + 784 = 54880
Step 71: 54880 + 784 = 55664
Step 72: 55664 + 784 = 56448
Step 73: 56448 + 784 = 57232
Step 74: 57232 + 784 = 58016
Step 75: 58016 + 784 = 58800
Step 76: 58800 + 784 = 59584
Step 77: 59584 + 784 = 60368
Step 78: 60368 + 784 = 61152
Step 79: 61152 + 784 = 61936
Step 80: 61936 + 784 = 62720
Step 81: 62720 + 784 = 63504
Step 82: 63504 + 784 = 64288
Step 83: 64288 + 784 = 65072
Step 84: 65072 + 784 = 65856
Step 85: 65856 + 784 = 66640
Step 86: 66640 + 784 = 67424
Step 87: 67424 + 784 = 68208
Step 88: 68208 + 784 = 68992
Step 89: 68992 + 784 = 69776
Step 90: 69776 + 784 = 70560
Step 91: 70560 + 784 = 71344
Step 92: 71344 + 784 = 72128
Step 93: 72128 + 784 = 72912
Step 94: 72912 + 784 = 73696
Step 95: 73696 + 784 = 74480
Step 96: 74480 + 784 = 75264
Step 97: 75264 + 784 = 76048
Step 98: 76048 + 784 = 76832
Step 99: 76832 + 784 = 77616

So, 784*99 = 77616