🏷️ Percentages
Percentages in the Wild
The number on the sale sign is lying to you. Here’s how to catch it.
A shop window says 25% off.
Your gut hears €25.
Your gut is about to lose money.
Start here
Meet the €40 hoodie
Sale rails, battery bars, match stats. They all use the same word: per cent, which means out of every hundred. Shops are betting you’ll read “25% off” and think “€25 off”. Time to make that a losing bet.
Your turn. Drag the bar (or tap the buttons) and watch what a discount does to the price: how much you pay, and how much comes off.
25% off
Every 1% you drag is another 40 cent off. The per cent is a slice of the price, not a price of its own.
So how much really comes off a €40 hoodie?
Pick a number. No take-backs.
The trap
The €25 mistake
A sign says 25% off a €40 hoodie. Quick: how much comes off? Answer before anything moves. No take-backs.
€40 cut into quarters. 25% is exactly one of them:
The secret is in the word.
Per cent means per hundred.
The why
Per cent means per hundred
Slice the €40 into 100 equal chips and each chip is worth 40 cent. That’s what 1% is. Every percentage is a stack of these. Drag across the pile and build your own.
25%
25 chips × 40c = €10.00
Find 1% first and the rest is stacking. That one move handles every percentage sum you’ll ever meet.
Doing the sums
The 10% trick
You don’t need a calculator in a shop. Find 10% first (slide the decimal point one step left), then scale up or down. Any price, any per cent. Watch the tempting answer sit beside the real one.
Now the part that catches people.
A percentage never travels alone.
It always belongs to whatever it’s a slice of.
The real twist
Down 20%, up 20%, not back where you started
A €50 pair of trainers goes into the sale at 20% off. A week later the shop puts the price back up by 20%. Sounds like a round trip. Run it.
€50.00
Before you press anything: will it land back on €50?
Battery at 37%. A striker’s 82% passes. “Up to 70% off.”
Same question, every time: how many out of a hundred?
And one question handles all of them: per cent of what? Ask that, and the number has to answer.
One more thing
Once you see it, it’s everywhere: your battery at 37%, a striker’s 82% pass accuracy, “up to 70% off” on a shop window, VAT sitting inside every receipt. All of them answer the same question (how much out of every hundred?) and one question back handles all of them: per cent of what?
Next time someone swears 25% off €40 saves €25, don’t argue. Ask what the 25 is out of, and let them work it out. This one’s yours now.