OK, let's work through this together. We're starting with 409 and we're going to multiply it by 10, which means we add 409 to itself 10 times.
Step 1: 0 + 409 = 409
Step 2: 409 + 409 = 818
Step 3: 818 + 409 = 1227
Step 4: 1227 + 409 = 1636
Step 5: 1636 + 409 = 2045
Step 6: 2045 + 409 = 2454
Step 7: 2454 + 409 = 2863
Step 8: 2863 + 409 = 3272
Step 9: 3272 + 409 = 3681
Step 10: 3681 + 409 = 4090

So, 409*10 = 4090