Slate: Calculator

Slate is eight everyday calculators in one, dressed in chalk on a slate board: keys that click like they mean it, and everything you actually need, nothing you don't.

EIGHT TOOLS, ONE KEYPAD

• Calculator: basic for everyday sums; one tap opens the scientific keys: trig and inverses, logs, roots, powers, factorials, π and e, degrees or radians. Percent works the way desk calculators always have (50 + 10% is 55), and the tape above the display remembers recent results, so tap one to use it again.

• Percent: discounts, markups, tips-of-the-tongue "what percent of what" sums.

• Date: days between dates, add or subtract days, work out an age.

• Tip: split the bill fairly, down to the cent. (Pro)

• Units: length, weight, volume, temperature and more. (Pro)

• Loan: repayments and total interest at a glance. (Pro)

• GST: add it to a quote or pull it out of a total, at any rate. (Pro)

• Exchange: convert currencies on European Central Bank reference rates, and keep the last table on the phone. (Pro)

Every tool runs on the same skinned keypad, and the system keyboard never appears.

EVERY SUM REMEMBERED

Slate keeps the calculations you finish, newest first. Tap one and it loads straight back into the tool that worked it out, ready to change. Clearing the list is two taps.

SKINS THAT CHANGE EVERYTHING

Slate ships in chalk. Slate Pro re-dresses every tool: Ledger's paper and ink, Terminal's green phosphor glow, Porcelain's clean white, Ember's warm coals, Drift's dusk violet, Blueprint's cyanotype lines. Every skin pairs with its own key sounds: Typewriter (with a carriage bell on equals), Beeps, Droplets, Woodblock, Hush and Abacus.

CAST IT

Put your working on the big screen: cast to a TV and Slate mirrors whichever tool is up, same numbers, same skin, while your phone stays the keypad. Walk away and an idle cast tidies itself up after a few minutes.

CALM ABOUT EVERYTHING ELSE

• No ads · No accounts · No subscriptions

• Slate uses the network for Exchange's published reference rates, for the store's billing for the one-time purchase, and for casting to your TV if you use it.

• We receive anonymous usage stats.

PAY ONCE, OWN IT

Slate is complete without paying: the full basic and scientific calculator, Percent, Date, the tape, the history, the chalk board and its key sounds. Slate Pro is a single one-time purchase that unlocks the other five tools and every skin and sound set, including the ones we add later. Pay once, own it forever, and no subscription, ever. Not sure yet? Pick a Pro calculator from the menu and it works for real for ten seconds, once a day for each one.

From Zone7 Studios, maker of Ethereal, Brume, Sylph and Lore.