A worker at the block factory packed blocks in 3 boxes of 1,000, 4 cases of 100, and 9 single blocks. How many blocks did the worker pack?

3,409 because 3 boxes of 1,000 is 3,000 because 1,000+1,000+1,000=3,000 and 4 cases of 100 is 400 because 100+100+100+100=400 and then just 9 single blocks so it's 3,000+400+9=3,409
I hope that this helped