Can You Solve This Math Riddle Without Guessing?
I came across a little math riddle that looks easier than it actually is.
Here’s the challenge:
A shop is having a sale. A backpack normally costs $80.
First, the shop gives you 20% off.
Then, at checkout, you get another 10% off the already discounted price.
What is the final price of the backpack?
Take a guess before looking at the answer.
Let's work it out
The first discount is pretty easy:
20% of $80 = $16
So:
$80 − $16 = $64
Now comes the part where people sometimes make the mistake of simply adding the discounts together and saying:
20% + 10% = 30%
That would give $56, but that's not actually correct.
The second 10% discount is taken from the new price of $64, not the original $80.
So:
10% of $64 = $6.40
Then:
$64 − $6.40 = $57.60
So the final answer is:
$57.60
If you want to check the percentage calculation without doing it manually, I sometimes use a free online calculator eg :- https://thecalcu.com/percentage-calculator/. It's handy for exactly these little everyday calculations.
The Trick
The answer isn't a 30% discount.
It's actually a 28% effective discount:
$80 − $57.60 = $22.40
$22.40 ÷ $80 × 100 = 28%
So the riddle's answer is $57.60, not $56.
Did you get it right before checking? 😄
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