Maybe use a scenario to show how you spent $82 of the $512 you originally had. For example, during your trip to the mall, you spent $2 dollars for a panda keychain. Then, you spent $10 for a Spiderman comic book. On your way home, there was a sale on the shoes you have always wanted, so you bought a pair of shoes for $70.
This scenario is useful because it can help you count 82 from 512 by breaking up the number. Doing so prevents you from over thinking the problem, etc.