OK, let's crack this. We're given 405 and our task is to multiply it by 17. Essentially, we'll be adding 405 to itself 17 times.
Step 1: 0 + 405 = 405
Step 2: 405 + 405 = 810
Step 3: 810 + 405 = 1215
Step 4: 1215 + 405 = 1620
Step 5: 1620 + 405 = 2025
Step 6: 2025 + 405 = 2430
Step 7: 2430 + 405 = 2835
Step 8: 2835 + 405 = 3240
Step 9: 3240 + 405 = 3645
Step 10: 3645 + 405 = 4050
Step 11: 4050 + 405 = 4455
Step 12: 4455 + 405 = 4860
Step 13: 4860 + 405 = 5265
Step 14: 5265 + 405 = 5670
Step 15: 5670 + 405 = 6075
Step 16: 6075 + 405 = 6480
Step 17: 6480 + 405 = 6885

So, 405*17 = 6885