Sure thing! We've got 819 and we're gonna multiply it by 86. That's the same as adding 819 to itself 86 times.
Step 1: 0 + 819 = 819
Step 2: 819 + 819 = 1638
Step 3: 1638 + 819 = 2457
Step 4: 2457 + 819 = 3276
Step 5: 3276 + 819 = 4095
Step 6: 4095 + 819 = 4914
Step 7: 4914 + 819 = 5733
Step 8: 5733 + 819 = 6552
Step 9: 6552 + 819 = 7371
Step 10: 7371 + 819 = 8190
Step 11: 8190 + 819 = 9009
Step 12: 9009 + 819 = 9828
Step 13: 9828 + 819 = 10647
Step 14: 10647 + 819 = 11466
Step 15: 11466 + 819 = 12285
Step 16: 12285 + 819 = 13104
Step 17: 13104 + 819 = 13923
Step 18: 13923 + 819 = 14742
Step 19: 14742 + 819 = 15561
Step 20: 15561 + 819 = 16380
Step 21: 16380 + 819 = 17199
Step 22: 17199 + 819 = 18018
Step 23: 18018 + 819 = 18837
Step 24: 18837 + 819 = 19656
Step 25: 19656 + 819 = 20475
Step 26: 20475 + 819 = 21294
Step 27: 21294 + 819 = 22113
Step 28: 22113 + 819 = 22932
Step 29: 22932 + 819 = 23751
Step 30: 23751 + 819 = 24570
Step 31: 24570 + 819 = 25389
Step 32: 25389 + 819 = 26208
Step 33: 26208 + 819 = 27027
Step 34: 27027 + 819 = 27846
Step 35: 27846 + 819 = 28665
Step 36: 28665 + 819 = 29484
Step 37: 29484 + 819 = 30303
Step 38: 30303 + 819 = 31122
Step 39: 31122 + 819 = 31941
Step 40: 31941 + 819 = 32760
Step 41: 32760 + 819 = 33579
Step 42: 33579 + 819 = 34398
Step 43: 34398 + 819 = 35217
Step 44: 35217 + 819 = 36036
Step 45: 36036 + 819 = 36855
Step 46: 36855 + 819 = 37674
Step 47: 37674 + 819 = 38493
Step 48: 38493 + 819 = 39312
Step 49: 39312 + 819 = 40131
Step 50: 40131 + 819 = 40950
Step 51: 40950 + 819 = 41769
Step 52: 41769 + 819 = 42588
Step 53: 42588 + 819 = 43407
Step 54: 43407 + 819 = 44226
Step 55: 44226 + 819 = 45045
Step 56: 45045 + 819 = 45864
Step 57: 45864 + 819 = 46683
Step 58: 46683 + 819 = 47502
Step 59: 47502 + 819 = 48321
Step 60: 48321 + 819 = 49140
Step 61: 49140 + 819 = 49959
Step 62: 49959 + 819 = 50778
Step 63: 50778 + 819 = 51597
Step 64: 51597 + 819 = 52416
Step 65: 52416 + 819 = 53235
Step 66: 53235 + 819 = 54054
Step 67: 54054 + 819 = 54873
Step 68: 54873 + 819 = 55692
Step 69: 55692 + 819 = 56511
Step 70: 56511 + 819 = 57330
Step 71: 57330 + 819 = 58149
Step 72: 58149 + 819 = 58968
Step 73: 58968 + 819 = 59787
Step 74: 59787 + 819 = 60606
Step 75: 60606 + 819 = 61425
Step 76: 61425 + 819 = 62244
Step 77: 62244 + 819 = 63063
Step 78: 63063 + 819 = 63882
Step 79: 63882 + 819 = 64701
Step 80: 64701 + 819 = 65520
Step 81: 65520 + 819 = 66339
Step 82: 66339 + 819 = 67158
Step 83: 67158 + 819 = 67977
Step 84: 67977 + 819 = 68796
Step 85: 68796 + 819 = 69615
Step 86: 69615 + 819 = 70434

So, 819*86 = 70434