Your kid does the math.
You pay what they earned.

It pays for practice, not for report cards. You set the rate and a daily cap, the balance grows as they work, and you hand over real cash when you decide. PiggyBankMath keeps the record so nobody has to remember who owes what.

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Free while in beta. No card.

How it actually works

Step 1 / The kid

Timed sessions at their level

Addition, subtraction, multiplication, division, or a mixed round pulling from all four. An optional five minute assessment places them where they actually are, and the difficulty range widens on its own as facts get locked in. You can re-run the assessment any time they jump ahead.
Step 2 / The balance

The balance grows as they go

Every completed session pays at the rate you set. When the day's total reaches your cap, the money stops but the practice does not. Each kid has their own balance, their own rate, and their own cap, so a nine year old and a twelve year old are not on the same deal.
Step 3 / The payout

You hit Mark as Paid

Cash, Venmo, whatever your family already does. When the money physically changes hands you mark it, all of it or part of it, and the balance updates. There is no processing, no debit card, and no request queue to approve: the app is the shared record, you are the bank.

It is real money, so it is built like it

You set the ceiling

Pick what a session is worth: a nickel, a quarter, whatever fits your week. Then set a daily maximum so a motivated kid on a rainy Saturday cannot run up a bill you never agreed to.

They cannot farm easy problems

An answer that is correct but slow usually means fingers were involved, and it does not count toward mastery here. A fact only counts as learned after three fast, correct answers on at least two different days. Grinding 2 + 2 for forty rounds pays nothing extra and teaches the app nothing.

Every balance change is explained

Adding five dollars for a birthday, or taking some back after a bad week, requires a reason in writing. Your kid sees that reason sitting next to the amount. A balance that moves with no explanation is exactly how a kid stops trusting the whole arrangement.

The ledger is yours

One click downloads every session, payout, and adjustment as a CSV you can open in Numbers, Excel, or Sheets. The amounts sum to the current balance, so you can check the app's math the same way you would check a bank statement.

The distinction that matters

It pays for effort, not for grades

Almost every argument against paying kids lands on the same objection, and it is a good one: tie money to a report card and you teach a kid to chase the number. Take the easier class. Do the minimum that scores. Lose interest the day the money stops.

That objection is about grades, and none of this touches a grade. There is no report card to upload and no test score to hit. A kid gets paid for sitting down and doing a round of practice, which is the part they actually control on a bad week. A slow answer still earns; it just does not count as mastered yet.

Which is also why the cap exists. Once the day's maximum is reached the money stops and the practice does not, so a kid who wants to keep going is never told the work stopped counting. The longer version of this argument is here, including the parts I think are genuinely unresolved.

The part I should say out loud

Paying a kid to do math is a fair thing to feel uneasy about. Plenty of parents think schoolwork should not carry a price tag, and I do not have a study that settles the argument. What I can tell you is what this thing actually does: it makes the deal explicit, it refuses to pay for slow guessing, and it leaves a record you both can look at.

I built it for my own two kids because I wanted that record and could not find it anywhere. It is free while I am still working out what it should be, and there is no trial quietly running out in thirty days. If it is not right for your family, that is a completely reasonable call to make.

Daniel, solo developer and the parent of the first two users

Try it for one week

Add a kid, pick a rate, and see what Friday's balance looks like. Setup takes about two minutes on the phone you are already holding.

Set up my first kid

Free while in beta. No card, no subscription, nothing to cancel.

Your kid does the math.You pay what they earned.