Let's roll up our sleeves and solve this. We have 819 and we're going to multiply it by 43, essentially adding 819 to itself 43 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

So, 819*43 = 35217