It’s billed as the calculator that won’t think until you do: if you give it something to evaluate, it will refuse to give you an answer until you give it an acceptable approximation.

On the surface, that’s a great idea. If I had a coffee for every time I’ve rolled my eyes at students, faced with $5 \times 7$, reaching for a calculator, I’d be bouncing off the walls even more than usual. In terms of getting students to think a little bit about their special trigonometric values (which I declined to learn by heart at school, instead recognising multiples of $\pi$ and $\sqrt{3}$ as they came up in the decimal places of my 1990s calculator) or arithmetic strategies, it ought to be a game-changer.

Unfortunately, there’s one major problem: students already have calculators. The effect of me giving it to students who don’t bring calculators to class has been a dramatic uptick in students bringing their calculators to class. There’s a mindset problem, too: the people who think this is an awesome idea (like me) are people who generally have decent arithmetic skills already. It’s like a device that helps someone quit smoking by firing a water-pistol in their face every time they light up. I’m sure it’s very effective, especially if used universally and early, but the people who think it’s a good idea probably aren’t the ones getting squirted, and the ones getting squirted will quickly find ways around it rather than learning the appropriate lesson. (See also: speed cameras.)

It’s a clever bit of technology – fitting the logic required to decide whether something is a reasonable answer into a calculator-sized, um, calculator is no mean feat at all, and while I haven’t run Matt Parker’s suite of tests on it, I haven’t noticed it doing anything untoward yet.

That said, as calculators go, it’s not much more advanced than the ones I was using in the late 1990s. It doesn’t spew out fractions of π or square roots (or even accept them as answers); it’s fussy about syntax (“50cos(π/6)” is not an acceptable input, as it’s missing a multiplication sign) and doesn’t do error messages at all, just flashes its cursor petulantly.

It’s also a hassle to order: it’s shipped from California, whence postage is expensive; import taxes and fees also bump up the price to the point where only about 50% of the money you spend on the calculator actually goes on the calculator itself.

The QAMA calculator is a cool proof of concept, and I really like it; much as I wish it was the tool to change the calculator-dependent world of secondary education, I fear it would prove hugely unpopular with students, who would simply find ways to work around its artificial demands.