Does Plus & Minus need an internet connection?

Only to buy or restore the unlock. Practice, handwriting recognition, history, and statistics all happen on the device, so they work the same in airplane mode. Buying and restoring go through the App Store or Google Play, and the app itself sends nothing to us.

Where is my child’s history kept, and how do I delete it?

The history of each session (the problems, whether each answer was right, how long it took, and the handwriting) is saved only on this device, and the statistics (the bar-chart button on the History screen) are worked out from it on the device. In Settings, Keep history sets how long it is kept (forever, 90 days, or 365 days), and Erase history deletes every session at once. Both ask a grown-up first (see below). Erasing cannot be undone. Deleting the app also deletes its history.

If your device backs up to iCloud, a computer, or your Google account, those backups may include the app’s data. They are controlled by you and by Apple or Google, not by us.

The app doesn’t read my child’s writing. What can we try?

• Write one digit per box, large and clear. After the last stroke the app waits a moment, so a two-stroke number like 4 isn’t read too early.
• When the app isn’t sure what was written, it doesn’t guess. The box blinks yellow and the eraser gets a yellow outline, as a sign to write it again.
• Tap the eraser to clear the answer and write it again.

If a digit is misread often, please email us which digit it is and whether a pen or a finger was used.

Can my child write with a finger, or only with a stylus?

Both. In Settings, Writing input has three choices: Auto ignores touch while a pen is in use (so a resting hand doesn’t leave marks), Pen only, and Finger allowed. Settings also let you choose the time per problem (5, 10, or 20 seconds) and the number of problems per session (5, 10, or 20).

What is free, and what does the purchase unlock?

Number pairs 5 to 9, mixed practice 5 to 9, the history, and the statistics are free. A one-time purchase unlocks number pairs 10 to 19, mixed practice 10 to 19 and 5 to 19, and the test: 20 mixed problems in a row, graded together at the end. There are no ads, no subscriptions, and no sign-in. With Family Sharing on the App Store, one purchase unlocks the app on your family’s devices.

How do I restore my purchase?

Usually you don’t have to. Each time the app starts or you come back to it, it asks the App Store or Google Play what you have bought, so reinstalling the app unlocks it by itself. If it still looks locked, open Settings → Purchase and tap Restore purchase while signed in with the account that made the purchase.

Why does the app ask a multiplication question?

Some things are for grown-ups: buying, opening the privacy policy link, erasing history, and changing how long history is kept. Before any of these, the app shows Grown-ups only and asks for the answer to a two-digit × one-digit multiplication, so a young child doesn’t do them by accident. A wrong answer brings a new question. Other settings, such as the time per problem, open without it.