Get fast at
mental math.
Sums is a calculator where you're the one doing the sums. Ten problems a day, the same for everyone on earth. Then practice that aims at your level — not the average one.
Ten problems.
One attempt.
Same for everyone.
A new set drops at midnight in your timezone. Finish it and you get your time, your marks and your rank for the day.
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A real ladder
Warm-up, arithmetic, percentages, money, an estimate, and a finisher that earns its name. Never ten of the same thing.
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Honest timing
The clock runs from the moment you start. Step away and it keeps running — so your rank means something.
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A streak you can miss
One free freeze a month covers a day you lost to life. No red banners, no guilt-tripping.
Share it as a picture of the device — never the answers
Twelve programs.
One keypad.
Three quick questions place you on a 0–100 scale. From there every problem aims at the edge of what you can do — hard enough to matter, easy enough to finish.
Press a key to see what it runs
LCD readouts.
Keys that press.
The daily is free.
Forever.
So are unlimited Sprint, Zen and Survival. Premium buys the quality of practice — difficulty that tracks you, the review queue, every mode, the archive and your full stats.
US prices — your store shows yours. Cancel anytime in the App Store or Google Play; we send a reminder before a trial ends, so nothing is charged silently. Refund policy.
No ads.
Not one.
There is no ad network in the app, in any tier. We do measure which channels bring people who stick around, which is why iOS asks about tracking on first launch. Say no and everything works exactly the same — the app never withholds a feature to punish a privacy choice. Details in the privacy policy.
FAQ
Is this a brain-training app?
No. We promise one thing and it is measurable: you get faster and more accurate at mental arithmetic, because that is exactly what you practise. No claims about memory, IQ or focus.
What happens if I leave in the middle of the daily?
Nothing is lost — you come back to the same problem. The clock keeps running, though, so a long break shows up in your time.
Does it work offline?
Yes. Problems are generated on the device, so the daily and all practice work with no connection. Only your rank for the day needs the internet, and it syncs when you are back.
Why don't I see my rank for the day?
Because too few people have finished that day's puzzle yet. A percentile from a handful of players is noise, so the device shows your time instead until the number means something.
Do I need an account?
No. There is no sign-up, no email, no password. Your progress lives on your device.
How do I cancel?
Where every other subscription lives: on iPhone in your Apple Account subscriptions, on Android in Google Play under Payments & subscriptions. There is a direct link in the app's settings.