Everyday Number Sense
Like Duolingo, but for Everyday Number Sense. Tomo turns the whole topic into a game you play five minutes a day, until it actually sticks.
For the part of you with thirty open tabs that never became anything.
A short one: 12 levels across 2 sections, about 24 minutes end to end, roughly 5 days at five minutes a day. It moves through Running the Quick Gut Check and Decoding the Spin. It starts from scratch.
Free forever · No credit card · iPhone & Android
Key ideas in Everyday Number Sense
- Dividing an astronomical national total by the population converts an abstract number into a daily individual habit
- 300 billion divided by 300 million is 1,000 eggs per person a year, which works out to nearly 3 eggs every single day for every person
- Translating a huge claim into daily human scale immediately flags whether it matches physical reality
- Rounding messy numbers to clean powers of ten (like 50 million divided by 50 thousand) lets you do instant mental estimation
- 50,000,000 / 50,000 is roughly $1,000 per household, providing an immediate ballpark
- A back-of-the-envelope test aims to find whether an answer is around 100, 1,000, or 10,000, not to calculate exact dollars
- Keeping a short mental list of anchor numbers—like your national budget, city size, or monthly living costs—grounds strange figures
- An unfamiliar claim can only be evaluated when held against a known, related benchmark of comparable scope
- Tacking decimals onto rough estimates signals false precision that hides how uncertain the data actually is
- Rough estimates inherently contain wide margins of error, so extra digits mislead the audience into believing exact counting took place
- A raw number is meaningless without a baseline: 5,000 lost packages out of 10,000 is a disaster, but out of 50 million is a 99.99% success rate
- Asking 'compared to what?' converts a standalone scary number into a baseline rate or percentage
- A billion is 1,000 times larger than a million, not just a little bigger
- Our minds naturally lump 'millionaire' and 'billionaire' into one vague 'super rich' category instead of seeing the thousandfold gap
- Mental number lines compress as numbers get huge, treating distinct orders of magnitude as nearly the same
- Translating huge abstract counts into time exposes gaps that bare zeros hide
You've tried the other tabs
Thirty open tabs. Four facts you actually kept.
You watched. You nodded. By Sunday it was gone.
One answer, then back to scrolling.
Eight weeks. You meant to finish. You didn't.
Tomo gives Everyday Number Sense the Duolingo treatment: levels, streaks, and quick quizzes that test what you just learned. That game loop is what the tabs above never had, so it's the one you actually finish.
Here's what playing it feels like
A real question from this course. Take your best guess.
A headline claims your country of 300 million eats 300 billion eggs each year. What does that break down to?
Get it right to open this lesson and 11 more in the app.
Where Everyday Number Sense takes you
Build an instinctive radar for whether real-world numbers make sense. Learn to spot misleading statistics, scale errors, and deceptive charts in headlines and daily life.
- 1
Running the Quick Gut Check
- The Back-of-the-Envelope Sanity Test
- Seeing Past Massive Scales
- 2
Decoding the Spin
- Untangling Percentages and Risk
- Catching Distorted Averages and Visuals
2 sections · 4 units · 12 levels. Built to play, not to enroll.
You pick the voice
Everyday Number Sense is taught in the The Professor style: clear, structured, thorough. Want a different feel? In the app you can spin up the same topic in any of Tomo's teaching styles. Same facts, totally different vibe.
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Start Everyday Number Sense today.
Download Tomo, search Everyday Number Sense, and play your first lesson in under a minute.