How well do you actually know prices? Take the test.

You have opinions about prices. Strong ones. You've muttered at a checkout screen this month. You have a firm position on whether groceries are outrageous, whether rent is insane, whether everything costs double now.

Here's my uncomfortable question: when did you last check whether your numbers are right?

Because here's the secret the entire inflation debate is built on: almost nobody actually knows what things cost. We know what things used to cost, when we first started paying attention, and we've been arguing from that ghost ledger ever since.

Today, instead of another opinion, I'm offering a mirror. Ten questions. Write your guesses down — actual numbers — before scrolling to the answers. No partial credit for vibes.

The test

Guess a specific number for each. Your local currency is fine for 1-6; use USD for the global items.

1. 1.A litre (or gallon) of milk at your usual supermarket, this week
2. 2.A dozen eggs
3. 3.A jar of honey
4. 4.A month of full-time infant daycare in your area
5. 5.A basic 65-inch 4K TV
6. 6.Your own monthly electricity bill, without looking
7. 7.A Big Mac in the United States
8. 8.A base iPhone in India
9. 9.What a $155 grocery cart from 1997 costs today
10. 10.What percentage smaller that “same” cereal box is versus a decade ago

The reveals

The Big Mac (7): about $5.79 in the US. Most people guess low, still anchored to the burger of their student years.

The iPhone in India (8): ₹125,900 for a 256GB Pro, roughly $1,517 — a 38 percent premium over the US price, in a country where the median formal worker earns about $385 a month. Nearly everyone guesses that poorer countries pay less. The opposite is true, and that single wrong assumption distorts how people reason about global inequality.

The 1997 cart (9): about $500, not the ~$312 the official inflation calculator predicts. If you guessed near $312, congratulations, you know the statistics; if you guessed near $500, you know the store. The gap between those two answers is the entire cost-of-living debate in one number.

The TV (5): under $300. Most people guess $600-1,000, because their TV anchor was installed decades ago and TVs are the rare item that collapsed — down 90-plus percent since 2000. Price blindness runs in both directions: we overestimate the collapsed stuff and underestimate the exploded stuff.

The daycare (4): US centre-based infant care averages around $19,000 a year, over $1,500 a month. People who've never bought childcare routinely guess half that, and it's the single most common source of “why are they always broke?” misjudgment of other families.

The shrinking box (10): typical shrinkflation moves cut 9 to 16 percent of the product while the price holds. A cereal box dropping from 18 to 15 ounces is a 17 percent per-ounce increase that most shoppers never register.

Items 1-3 and 6: check against your own store and your own bill. Be honest about the gaps.

Individual items from that 1997 cart, for your scoring pleasure:

Why you failed (everyone fails)

Your errors weren't random, and they weren't stupidity. They were four well-documented bugs firing at once.

1. 1.You never read the price in the first place. For routine purchases, price memory is implicit: your brain files a vague “normal-ish” and moves on, retrieving it later through lazy shortcuts rather than actual numbers.
2. 2.Your anchors are ancient. The first prices you absorbed act as anchors that drag every later judgment toward them; the effect is among the most robust in psychology and persists for weeks even when the anchor is meaningless, like digits of your own social security number. Your first rent, your first tank of gas — those aren't memories, they're calibration errors with tenure.
3. 3.You only file the increases. People weight rising prices far more than falling ones; strip the ignored price declines out of the index and the gap between perceived and actual inflation almost disappears. Your internal ledger is an outrage diary, not an accounting document.
4. 4.The shelf is gaslighting you. Retailers actively supply fake reference points — the eternal “was $89.99, now $49.99” — because externally supplied anchors measurably bend what you'll judge as fair and what you'll pay. Meanwhile shrinkflation, “a tax on consumer attention,” harvests the gap between the package and your memory of the package.

Why it's worth fixing

This isn't trivia. A miscalibrated price sense costs you money and judgment in specific, compounding ways.

You can't spot a genuinely good deal, because “50% off” only means something relative to a true price you don't know. You can't detect shrinkflation without a unit-price instinct. You can't budget accurately with a mental ledger that logs increases and deletes decreases. You can't negotiate salary sensibly without knowing what your cost of living actually did this year, as opposed to what the headline says the average person's did.

And, maybe most corrosive of all, you can't argue fairly — with your parents, your partner, or the internet — when both sides are quoting numbers from different decades.

Price literacy is the closest thing personal finance has to a foundational skill, and it's the one nobody teaches, because everyone assumes they already have it. You just took the test. Do you?