Everyday Arithmetic
Build genuine confidence with the numbers you encounter every day. Master mental math shortcuts, clear-headed multiplication and division, and practical mastery of fractions, decimals, and negative values.
Like Duolingo, but for Everyday Arithmetic. Tomo turns the whole topic into a game you play five minutes a day, until it actually sticks.
23 levels across 4 sections, about 46 minutes end to end, roughly 9 days at five minutes a day. It moves through Mental Fluency with Everyday Sums; Scaling Up and Sharing Out; Fractions, Decimals, and Proportions; and The Rules of the System. It starts from scratch.
Free forever · No credit card · iPhone & Android
Key ideas in Everyday Arithmetic
- Mental addition is usually faster left-to-right because dealing with the largest place values gives a quick estimate first
- Breaking two-digit numbers into tens and ones allows you to add the tens first, then add the ones, and combine the totals
- Numbers ending in 8 or 9 are very close to round multiples of ten
- Adding an easier round number adds too much, so you must subtract the extra amount at the end to compensate
- 57 needs 3 more to reach the next clean multiple of ten, which is 60
- Splitting a number into two parts lets you use the first part to reach a friendly ten and the leftover part to finish the sum
- Because addition order does not matter, you can rearrange a long list of numbers to group pairs that make 100 first
- Complementary pairs have ones digits that add to 10 and tens digits that add to 90 (giving 100 total)
- Subtraction measures the distance or gap between two numbers on a number line
- Viewing subtraction solely as 'taking away' makes close numbers like 82 and 79 tedious to solve, while viewing it as distance makes the answer an easy 3 steps
- Counting up starts at the smaller number and hops to the next clean landmark (ten)
- Hopping by friendly tens and ones eliminates the need to borrow backwards across columns
- Summing the hop sizes gives the total distance between the numbers
- Adding or subtracting the exact same amount to both numbers shifts both points along the number line without changing the distance between them
- Bumping 29 up by 1 makes it an easy 30, so bumping 63 up by 1 turns the problem into 64 - 30 = 34
- Adding mentally from left to right by starting with the largest place values
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 Arithmetic 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.
Why are numbers that end in 8 or 9 special when doing math in your head?
Get it right to open this lesson and 22 more in the app.
How to learn Everyday Arithmetic, step by step
Go in order. 23 short levels across 4 sections, about 46 minutes in all, five minutes a day.
- 1
Mental Fluency with Everyday Sums
- Friendly Numbers and Mental Addition
- Subtraction as Distance and Change
- 2
Scaling Up and Sharing Out
- Multiplication Through Grids and Decomposition
- Division and Fair Shares
- 3
Fractions, Decimals, and Proportions
- Fractions as Relations and Measurements
- Decimals and Percentages in Practice
- 4
The Rules of the System
- Order of Operations and Sanity Checks
- Negative Numbers and Direction
4 sections · 8 units · 23 levels. Built to play, not to enroll.
Questions about Everyday Arithmetic
How do I learn Everyday Arithmetic?
Go in order: start with Mental Fluency with Everyday Sums, then Scaling Up and Sharing Out, then Fractions, Decimals, and Proportions, then The Rules of the System. On Tomo that's 23 short levels, about 46 minutes in all, played five minutes a day. Start free and play the first level in under a minute.
Is there a Duolingo-style app for Everyday Arithmetic?
Yes. Tomo works like Duolingo: short daily lessons, streaks and quick quizzes. Everyday Arithmetic is one of its free courses, and you can type any other topic to get a course of your own.
Is the Everyday Arithmetic course free?
Yes. Everyday Arithmetic is playable on Tomo's free plan, which doesn't expire. No credit card, no waitlist. Download the app and start your first lesson.
How long does it take to learn Everyday Arithmetic?
23 levels across 4 sections, about 46 minutes of play in total. It's built for five minutes a day, so you finish it a little at a time instead of all at once.
Do I need any background to start Everyday Arithmetic?
No. It's pitched at a beginner level, so it starts where you are and builds up. If you can tap a phone, you can start.
Tomo is in ChatGPT
Tomo is also a ChatGPT plugin: the same playable courses, built and played inside your chat.
Add Tomo to ChatGPT- What to ask
- “Make me a Tomo course on black holes.” “Turn this chat into a Tomo course.”
- What you get
- Quick questions with instant feedback, hearts and stars, ready to play in about a minute.
- Where it goes
- No sign-up to start. Connect your Tomo account and your streak carries on in the app.
You pick the voice
Everyday Arithmetic is taught in the Explain Like I'm 5 style: no big words. promise.. 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 Arithmetic today.
Download Tomo, search Everyday Arithmetic, and play your first lesson in under a minute.