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Frequently asked

Where do hints come from?

Three ways.

• 5 hints when you install the app.
• 2 hints per ad you choose to watch — from More → Get hints, or from the puzzle when you run low.
• Attendance rewards: 2 at 5 days, 3 at 10, 4 at 15, 5 at 20, 7 at 25 and 10 at 30 days in a month.

There is no automatic daily grant.

The hint didn't just give me the answer

That is on purpose. Instead of filling in a square, a hint names the technique, highlights the cells the deduction rests on, and tells you why that digit has to go there. Read it once and you can usually find the next one yourself.

To go deeper, open Learn on that book in the Course tab — there is a lesson on the same technique.

What happens when I run out of hearts?

The game does not end. It simply carries on, quietly. What stops is the red marking of wrong squares — with no hearts left, pointing at every mistake would just be nagging.

To get them back, tap the hearts at the top of the screen and watch a short ad to refill all three.

What's the difference between Learn, Drill and Solve?

Tap a book in the Course tab and three buttons appear.

• Learn — a lesson on the technique, walked through one step at a time on a real board.
• Drill — that one technique on its own: find it, and the app grades you.
• Solve — a puzzle whose last gate is exactly that technique.

Can I replay a puzzle I've solved?

No, and that is deliberate — it protects your record. Replaying a puzzle you already know the answer to would make your times and score say something other than how well you play.

Tap Solve again and you get a fresh puzzle from that book. There are 2,000 in each.

My progress isn't showing on my other device

Three things to check.

• Both devices are signed in to the same Apple Account
• This app is switched on under Settings > Apple Account > iCloud
• The iCloud row on the app's More screen reads "On"

If it reads "This device only", iCloud is unavailable and your record is being kept on that device alone. Sync can also take a little while rather than happening instantly.

I want to erase everything

More → Erase all records. We ask twice before doing it.

Your times, scores and saved boards disappear from both the device and iCloud, and from any other device on the same account. Your hints remain.

I'd rather not watch ads

You don't have to. There are no banners and nothing that blocks the screen. A short video plays only when you tap to get more hints or to bring your hearts back.

Without ever watching one you can still solve all 10,000 puzzles, and every lesson and drill is open to you.

Does it work offline?

Yes. All 10,000 puzzles ship inside the app. On the train, on a plane, anywhere. A connection is needed only for ads and for iCloud sync.

How do I change the app's language?

It follows your device. To set it just for this app, go to Settings > Apps > Sudoku Classroom > Language.

English, Korean, Japanese, Chinese (Simplified), German and Spanish are supported.