OK, let's crack this. We're given 839 and our task is to multiply it by 29. Essentially, we'll be adding 839 to itself 29 times.
Step 1: 0 + 839 = 839
Step 2: 839 + 839 = 1678
Step 3: 1678 + 839 = 2517
Step 4: 2517 + 839 = 3356
Step 5: 3356 + 839 = 4195
Step 6: 4195 + 839 = 5034
Step 7: 5034 + 839 = 5873
Step 8: 5873 + 839 = 6712
Step 9: 6712 + 839 = 7551
Step 10: 7551 + 839 = 8390
Step 11: 8390 + 839 = 9229
Step 12: 9229 + 839 = 10068
Step 13: 10068 + 839 = 10907
Step 14: 10907 + 839 = 11746
Step 15: 11746 + 839 = 12585
Step 16: 12585 + 839 = 13424
Step 17: 13424 + 839 = 14263
Step 18: 14263 + 839 = 15102
Step 19: 15102 + 839 = 15941
Step 20: 15941 + 839 = 16780
Step 21: 16780 + 839 = 17619
Step 22: 17619 + 839 = 18458
Step 23: 18458 + 839 = 19297
Step 24: 19297 + 839 = 20136
Step 25: 20136 + 839 = 20975
Step 26: 20975 + 839 = 21814
Step 27: 21814 + 839 = 22653
Step 28: 22653 + 839 = 23492
Step 29: 23492 + 839 = 24331

So, 839*29 = 24331