Whetstone Support

Whetstone: Mental Math. A daily number workout for iPhone and iPad.

• What Whetstone is
• Requirements
• Levels, tries and the clock
• Typing answers
• The Daily Workout, streak and edges
• Progress charts
• Whetstone Full: purchase and restore
• Progress and iCloud sync
• Troubleshooting

What Whetstone is

Whetstone sharpens your mental arithmetic, a few minutes a day. A path of 48 levels in 8 stages (named after the grits of a sharpening stone, from 120 to 8000) goes from two-digit sums and products to long division, negative numbers, order of operations, squares and roots, decimals, percentages and fractions. Each level is ten problems.

Everything runs on your device. The app works offline.

Requirements

• iPhone or iPad with iOS 18 or later.
• No account and no internet connection needed. iCloud sync and purchases use your Apple Account when you are online.

Levels, tries and the clock

• Four tries per problem. A wrong answer stays on screen, crossed out. Typing the same wrong answer again does not use a try. After the fourth miss the answer is shown with a one-line method.
• Points and stars. 3 points for a first-try answer, 2 for the second try, 1 for the third or fourth. 18 points (of 30) clear a level with one star, 24 give two, 28 give three.
• The clock counts up while you solve; there is no time limit and time never changes your points. Tap ⏸ to pause: the problem is hidden and the clock stops. The app also pauses when you leave it.
• Any level, any time. The Path suggests the next level, but you can play any level you have unlocked. Long-press a level to see your best score and time.
• A level you leave is saved: Continue appears on Today and on the Path.

Typing answers

• Remainders (for example 34 ÷ 8): type the quotient, tap R, then the remainder: 4 R 2.
• Negative numbers: tap − (the key appears only when an answer can be negative).
• Decimals: tap .; 6.30 and 6.3 are both right.
• Fractions: type 7/4. Fractions must be in lowest terms; the app tells you (without using a try) if they are not.
• On iPad with a keyboard: digits, − . / R, Return to submit, Delete, Esc to pause.

The Daily Workout, streak and edges

• Daily Workout: ten problems a day, mostly from your next level, plus the skills that are getting rusty and problem types you recently missed. It is the same all day on all your devices.
• Streak: the days in a row you finished the workout. Seven days in a row earn a rest day, which covers one missed day.
• Edge: how sharp each skill is (0–100), from your recent first-try answers. It slowly dulls when you do not practise that skill; tap it to practise ten problems.
• Reminder: Settings → Daily reminder, at the time you choose. It is skipped once today's workout is done.

Progress charts

The Progress tab shows problems per day, how often you are right on the first try, your speed by week (for all skills or one), your edge per skill, a practice calendar and the levels you have cleared.

Whetstone Full: purchase and restore

Stages 1 and 2 (12 levels, all four operations), the Daily Workout and all the charts are free. One purchase, Whetstone Full, unlocks stages 3 to 8 (36 more levels). No subscription, no ads, and it is shared with your family through Family Sharing.

• Buy: tap a locked level, or Settings → Unlock Whetstone Full.
• New device or reinstall: Settings → Restore Purchases, signed in with the same Apple Account.
• Family: with Family Sharing turned on for purchases, family members open the levels with Restore Purchases.
• Refunds are handled by Apple: reportaproblem.apple.com.

Progress and iCloud sync

Signed in to iCloud, your stars, streak and charts are the same on your iPhone and iPad, without an account. A level in progress stays on the device where you started it. Settings → Delete all progress clears your progress on all your devices.

Troubleshooting

• Progress does not appear on my other device. Check that both are signed in to the same Apple Account with iCloud Drive on, and open the app on both; sync can take a minute.
• The levels did not unlock after buying. Settings → Restore Purchases. If a purchase is waiting for approval (Ask to Buy), the levels open as soon as it is approved.
• No sound. Sounds follow the silent switch; check Settings → Sounds.
• No reminder. Allow notifications for Whetstone in the iOS Settings app, then turn the reminder off and on again.