SingingNumbers Calculator

Zadio

About this app

SingingNumbers is a calculator that turns arithmetic into music.

Tap a digit and you hear its note. Operators (+ - x ÷) do not play
a note themselves; they shape the articulation of the next digit's
note: + accents it, - softens it, x makes it legato (smooth), ÷
inserts a short rest before it. Hit "=" — the press itself is
silent, but it triggers playback of the full expression plus the
resulting digits as a short melody. The audio feedback also makes
it easier to verify what you typed without taking your eyes off the
work in front of you.

WHAT'S INSIDE

• Calculator — Material 3 keypad with light, dark, and dynamic themes
(Android 12 and newer). Generous, accessible buttons with a haptic
tick on every press.
• Big Calculator mode — flip to a 24-key keypad and compose with
notes 0–23 (chromatic). Mix small and big notes in the same
expression; the playback always knows which is which.
• Saved — keep a personal library of expressions you like, replay
them with a single tap, rename them, delete them. Nothing is
saved unless you explicitly tap "Save".
• Scales — pick the musical scale the calculator sings in.
• Octaves — pick the octave range the calculator sings in.
• Instruments — pick which synthesised instrument timbre you prefer.
• Settings — tempo, rhythm, pitch, and haptic feedback toggles.

PRIVACY YOU CAN ACTUALLY VERIFY

• One permission only. The app declares a single Android permission,
VIBRATE, used only for the short haptic tick on each button press.
VIBRATE is a normal-protection permission, so Android grants it
automatically — you are never asked for it at install or runtime,
and it does not transmit or collect any data. No internet, no
microphone, no storage, no contacts, no location, no camera.
• 100% offline. The INTERNET permission is not declared, so the app
cannot connect to a network even if it wanted to. No analytics.
No crash reporting. No tracking SDKs.
• No data sent off your device. A handful of preferences (scale,
octave, instrument, language, tempo / rhythm / pitch / haptic
settings, Big Calculator toggle) and any expressions you tap
"Save" on are kept on the device only — never synced, never
transmitted, never visible to any other app, removed when you
uninstall.
• No ads. No in-app purchases. No "premium" tier locked behind a
paywall. The app is free, in every sense of the word.

WHO IT'S FOR

• Anyone who wants a small, fast, dependable calculator that doesn't
try to monetise their attention.
• Engineers, students, accountants, and anyone who appreciates that
audio feedback is a faster way to spot a mistyped digit than a
second look at the screen.
• Anyone tired of "calculator" apps that ship 60 MB of analytics
and ad SDKs to do what 50 KB of arithmetic could do in 1980.

ACCESSIBILITY

• Every button has a meaningful contentDescription for TalkBack.
• The result line is a polite live-region so screen readers
announce every change.
• System font scaling is fully respected.
• Dark theme follows the system setting.

AGE RATING

Rated Teen (13+) on Google Play. The app collects no data and contains
no ads, in-app purchases, or mature content; younger users can use it
safely under parental discretion.

The full privacy policy and contact details are linked from this
Play Store listing.

What’s new

What's new in 0.2.2

• Compliance with Google Play's 16 KB memory page-size policy
(enforced 2025-11-01). The native audio engine, the bundled
Oboe audio library, and the C++ runtime are now all built
with 16 KB-aligned ELF segments so the app runs natively on
Android 15 devices that use 16 KB pages.
• Internal: NDK r26.1 → r27.0, Oboe 1.9.0 → 1.10.0.
• No user-visible behaviour changes — same Calculator, Big
Calculator, Scales, Instruments, and Saved screens as 0.2.1.