How do you determine the change received when paying with a $20 bill after a purchase of $11.94?

To determine the change received after making a purchase, you need to subtract the total cost of the purchase from the amount you paid. In this instance, you start with the $20 bill and subtract the purchase amount of $11.94.

This calculation gives you the amount of change you will receive. Performing the subtraction:

$20.00 - $11.94 = $8.06

Therefore, the change received when you pay with a $20 bill after an $11.94 purchase is $8.06. This method is the most straightforward way to calculate how much money you should get back after your transaction.

Looking at the other options, adding the total purchase to the bill does not provide useful information about change; calculating taxes is unnecessary for determining the change amount; and finding the total cost of the purchase does not directly lead to calculating your change either.