8: A shop decreases all its prices by \( 10 \% \). A week later the shop increases all prices by \( 10 \% \). What is the overall change?

After the shop decreases its prices by \( 10\% \), the prices are at \( 90\% \) of the original. If we represent the original price as \( P \), the new price becomes \( 0.9P \). When the shop later increases this reduced price by \( 10\% \), the calculation is as follows: \( 0.9P \times 1.1 = 0.99P \). This means the final price is \( 99\% \) of the original price, resulting in an overall decrease of \( 1\% \). Now, isn't it wild how that initial discount came back to bite? A simple \( 10\% \) increase on a reduced price doesn’t get you back to square one! It's a classic example of how percentages can play tricks on your wallet. Always keep an eye on those tiny percentage shifts because they can add up to a surprising outcome!