OK, let's crack this. We're given 345 and our task is to multiply it by 19. Essentially, we'll be adding 345 to itself 19 times.
Step 1: 0 + 345 = 345
Step 2: 345 + 345 = 690
Step 3: 690 + 345 = 1035
Step 4: 1035 + 345 = 1380
Step 5: 1380 + 345 = 1725
Step 6: 1725 + 345 = 2070
Step 7: 2070 + 345 = 2415
Step 8: 2415 + 345 = 2760
Step 9: 2760 + 345 = 3105
Step 10: 3105 + 345 = 3450
Step 11: 3450 + 345 = 3795
Step 12: 3795 + 345 = 4140
Step 13: 4140 + 345 = 4485
Step 14: 4485 + 345 = 4830
Step 15: 4830 + 345 = 5175
Step 16: 5175 + 345 = 5520
Step 17: 5520 + 345 = 5865
Step 18: 5865 + 345 = 6210
Step 19: 6210 + 345 = 6555

So, 345*19 = 6555