Mental maths for the money you actually deal with.

Countera is an Android app that trains the mental arithmetic people do with money: discounts, unit prices, best value, splitting a bill, and working out what you are still owed. It gives you a real skill rating, the Money Fluency Score, and an optional worldwide leaderboard.

No. Practice works offline and needs no account. Signing in with Google is optional and only needed to join the leaderboard.

Nothing stops you, and nothing checks. It only fools you, though.

The score is there to tell you how your own mental arithmetic is doing, and the questions get harder as it rises, so a score earned with a calculator only brings harder questions you cannot do in your head.

It is a skill rating, not a points total. It combines five ratings, one each for addition, subtraction, multiplication, division and percentages, and it rises as you get harder questions right.

Only a wrong answer lowers it. On an Exact Only question, anything other than the exact answer is wrong.

Missing a question that is easy for you costs more than missing a hard one. Each answer moves the rating for one kind of arithmetic, and your score combines five of them, so it moves about a fifth as much. Your first 20 answers of each kind move in bigger steps.

Very rarely, an update changes the scoring rules. Your whole history is then scored again under the new rules, which can move your score.

The top of every question card says how it will be graded. Exact Only means only the exact answer counts. Close Counts means near answers earn credit too, and an answer that rounds correctly counts as exact.

Close Counts is used where estimating is the real skill, such as discounts, tax, and how many you can afford. Exact Only is used where a near answer is no use, such as splitting a bill, what is still owed, or picking the best value.

In the Practice Room, small sums are Exact Only and bigger ones are Close Counts, and every percentage drill is Close Counts.

Near answers only count on Close Counts questions, and how near is judged by the size of the answer.

For an answer of 57,601: 57,601 is exact. Within 100, such as 57,600 or 57,700, is very close. Within 1,000, such as 57,000, 57,500 or 58,000, is close. Anything further, such as 56,000, is wrong.

For an answer of 433: 432 or 434 is very close, and anything from 423 to 443 is close.

Small answers have one extra rule: within 1 of the answer rounded to a whole number is close. If a question works out to 3.96, typing 4 counts as exact, because an answer that rounds correctly is the answer, and 3 or 5 is close.

On the result screen, Very Close and Close are counted together as Close, and Wrong is counted as Missed.

No. The keypad has digits only, and every answer is a whole number.

When the true answer is not whole, the question is Close Counts and the nearest whole number counts as exact. Questions that demand an exact answer are built so the answer is always whole. After a near answer, the result may still show the exact figure, such as Answer: 3.96.

For your score, only when you are slow. Each question has an expected time that grows with its size. An exact answer inside that time raises your score in full, however quick you were. A slower exact answer still raises it, just by less. Speed never lowers your score, and it makes no difference to a near answer.

For points, speed matters more. An exact answer earns 12 points when quick, 10 on time, 6 when slow and 1 when very slow.

They are the five bands your Money Fluency Score climbs through:

• Foundation: where everyone starts, getting comfortable with numbers.
• Steady, from 1,080: reliable with everyday calculations.
• Agile, from 1,210: quicker, with less hesitation.
• Sharp, from 1,350: real number sense.
• Fluent, from 1,500: the numbers arrive without being worked out.

The line beside your band on Today, such as 71 to Steady, is how much further your score has to rise to reach the next band. It counts score, not points.

Because Fluent means fluent in all money maths. Your score combines all five kinds of arithmetic, including any you have never practised, which sit at 1,000. No kind counts for more than 200 above the average of the other four.

So with four kinds at 1,000, the fifth counts as 1,200 at most, whatever its real rating, and your score tops out at 1,040, which is still Foundation. Fluent starts at 1,500.

Your real rating for each kind is on Progress, under Stats.

Points reward effort. Every answer earns at least 1, and a quick exact answer earns the most:

• Exact: 12 when quick, 10 on time, 6 when slow, 1 when very slow.
• Very close: 5, or 1 when very slow.
• Close: 3, or 1 when very slow.
• Wrong: 1.

Quick means inside 80% of the time expected for that question, slow means up to one and a half times it, and very slow means longer. Your total is on Today and on Progress, under Achievements.

Accuracy is the share of your answers that were exactly right. Closeness is how near your answers land on average: an exact answer counts as 100%, one out by a tenth as 90%, and one out by as much as the answer itself as nothing.

For example, 10 answers with 6 exact and 4 each out by a tenth give an Accuracy of 60% and a Closeness of 96%. Closeness rounds down, so 100% only ever means every answer was exact.

Most money questions are not answered exactly in real life, so a lower Accuracy with a high Closeness is a good place to be. For a wrong Best Value pick, Closeness uses how much more your pick cost for each item.

If you are not sure, pick Money Mixed. It is at the top of the Practice screen and draws from everything.

• Shopping: discounts, the price before a discount, and tax.
• Margin: buying, selling, and the profit.
• Rates: unit prices, and how many you can get.
• Credit: what is owed, paid, and still outstanding.
• Splitting: bills, and cost per use.
• Best Value: the cheapest offer per item.

The Practice Room below has plain sums with no money story, one kind of arithmetic at a time or mixed. Every mode feeds the same five ratings, and nothing is locked.

You see four offers, each a number of items for a price. Tap the one that costs least for each item. There is no keypad: the tap is your answer, and only the best offer counts.

The biggest pack is not always the best, the best can be in any position, and the offers are never so close that picking is a coin toss. The sum underneath is division, so these count toward your division rating.

Afterwards the best offer is marked with a tick, and a wrong pick with a cross. They have their own mode, Best Value, and also come up in Money Mixed.

Six questions unless you choose otherwise. On the Practice screen, under How Many, you can pick 6, 12, 25, 50 or 100.

It goes back to 6 each time you open the Practice screen, so one long session does not become your daily session. Keep Going on the result screen repeats the length you just did.

Yes. In Settings, choose Answer Entry and then Right to Left, or tap the direction button above the keypad during a question. Your choice is remembered.

With Right to Left, each new digit goes in front, the way you work a sum from the units up, so typing 9 then 6 gives 69. The delete key removes the digit you typed last.

Any calendar day, in your phone's own time, on which you answer at least one question. One answer is enough, even a wrong one.

If you practised yesterday but not yet today, your streak still stands for all of today. It only breaks when a whole day goes by with nothing answered. So if you practise on Monday evening, the streak is safe until midnight at the end of Tuesday.

The streak card shows the day your streak started, your longest streak, and this week. Your longest streak never goes down.

Shields are on Progress, under Achievements. They reward consistency and firsts, never how much you do in one go.

• A Week Running: practise 7 days in a row.
• A Month Running: practise 30 days in a row.
• A Hundred Days: practise 100 days in a row.
• A Perfect Session: get every question in a session exactly right.
• Off the Bottom Rung: reach Steady, a Money Fluency Score of 1,080.
• Strong All Round: get all five kinds of arithmetic to 1,080 or higher at the same time.

The streak shields count your longest run ever, so a broken streak does not take them away. Off the Bottom Rung and Strong All Round are earned the moment you reach them, and stay earned even if your score slips back afterwards.

Rupees, dollars, pounds, euros or yen, with the digit grouping and units you actually use. Currency and region can be chosen independently.

This Week ranks points earned this week, so effort decides it. All Time ranks the Money Fluency Score, so skill decides it.

The week is the same for everyone: Monday 00:00 to Sunday 23:59 UTC. In India that is 5:30 on Monday morning. The board shows how long is left.

World counts every player; your region counts only players who chose the same region in Settings. Changing your region moves you to that region's board.

Only your nickname and colour, your band, your score, your streak, your shields and when you joined. Never your email, your real name or your answers.

Only your nickname and your figures: your score and band, streaks, best score, shields earned, questions solved and this week's points. Your practice history and individual answers are never uploaded.

Your practice history lives on your phone, so uninstalling removes it unless your phone backs it up.

Android backs up app data to your own Google Drive, so restoring a backup on a new phone usually brings your history with it. Countera cannot check that, so do not rely on it. Your leaderboard account is kept on the server either way: sign in on the new phone to carry on.

In the app: Settings, then Delete Account. Without the app: countera.suryaelite.com/delete-account. Either way, deletion is immediate.