For whole numbers, determining place values is super easy. I'll show you how.
First of all, let's establish some of the place values. Let's just use 12345 as our number.
1 - ten-thousands, 2 - thousands, 3 - hundreds, 4 - tens, 5 - ones.
This list goes on and on, as numbers get bigger. Some more place values are ones, tens, hundreds, thousands, hundred-thousands, millions, ten-millions, hundred-millions, billions, etc.
Now, let's go to the number 8091. In this number there's only 4 place values.
8 - thousands
0 - hundreds
9 - tens
1 - ones
You now have your answer. The place value of 8 in 8091 is thousands.
Hope this answer helped you out. :)