Alright, let's solve this math problem step by step. First, we have the number 858. Next, we see the multiplication sign, which means we need to multiply something. And what are we multiplying it by? We multiply it by 78. So, we're going to take the number 858 and add it to itself 78 times.
Step 1: 0 + 858 = 858
Step 2: 858 + 858 = 1716
Step 3: 1716 + 858 = 2574
Step 4: 2574 + 858 = 3432
Step 5: 3432 + 858 = 4290
Step 6: 4290 + 858 = 5148
Step 7: 5148 + 858 = 6006
Step 8: 6006 + 858 = 6864
Step 9: 6864 + 858 = 7722
Step 10: 7722 + 858 = 8580
Step 11: 8580 + 858 = 9438
Step 12: 9438 + 858 = 10296
Step 13: 10296 + 858 = 11154
Step 14: 11154 + 858 = 12012
Step 15: 12012 + 858 = 12870
Step 16: 12870 + 858 = 13728
Step 17: 13728 + 858 = 14586
Step 18: 14586 + 858 = 15444
Step 19: 15444 + 858 = 16302
Step 20: 16302 + 858 = 17160
Step 21: 17160 + 858 = 18018
Step 22: 18018 + 858 = 18876
Step 23: 18876 + 858 = 19734
Step 24: 19734 + 858 = 20592
Step 25: 20592 + 858 = 21450
Step 26: 21450 + 858 = 22308
Step 27: 22308 + 858 = 23166
Step 28: 23166 + 858 = 24024
Step 29: 24024 + 858 = 24882
Step 30: 24882 + 858 = 25740
Step 31: 25740 + 858 = 26598
Step 32: 26598 + 858 = 27456
Step 33: 27456 + 858 = 28314
Step 34: 28314 + 858 = 29172
Step 35: 29172 + 858 = 30030
Step 36: 30030 + 858 = 30888
Step 37: 30888 + 858 = 31746
Step 38: 31746 + 858 = 32604
Step 39: 32604 + 858 = 33462
Step 40: 33462 + 858 = 34320
Step 41: 34320 + 858 = 35178
Step 42: 35178 + 858 = 36036
Step 43: 36036 + 858 = 36894
Step 44: 36894 + 858 = 37752
Step 45: 37752 + 858 = 38610
Step 46: 38610 + 858 = 39468
Step 47: 39468 + 858 = 40326
Step 48: 40326 + 858 = 41184
Step 49: 41184 + 858 = 42042
Step 50: 42042 + 858 = 42900
Step 51: 42900 + 858 = 43758
Step 52: 43758 + 858 = 44616
Step 53: 44616 + 858 = 45474
Step 54: 45474 + 858 = 46332
Step 55: 46332 + 858 = 47190
Step 56: 47190 + 858 = 48048
Step 57: 48048 + 858 = 48906
Step 58: 48906 + 858 = 49764
Step 59: 49764 + 858 = 50622
Step 60: 50622 + 858 = 51480
Step 61: 51480 + 858 = 52338
Step 62: 52338 + 858 = 53196
Step 63: 53196 + 858 = 54054
Step 64: 54054 + 858 = 54912
Step 65: 54912 + 858 = 55770
Step 66: 55770 + 858 = 56628
Step 67: 56628 + 858 = 57486
Step 68: 57486 + 858 = 58344
Step 69: 58344 + 858 = 59202
Step 70: 59202 + 858 = 60060
Step 71: 60060 + 858 = 60918
Step 72: 60918 + 858 = 61776
Step 73: 61776 + 858 = 62634
Step 74: 62634 + 858 = 63492
Step 75: 63492 + 858 = 64350
Step 76: 64350 + 858 = 65208
Step 77: 65208 + 858 = 66066
Step 78: 66066 + 858 = 66924

So, 858*78 = 66924