iOS 11: New iPhone calculator adds animations that make adding up difficult

Sometimes, 1 + 2 + 3 doesn't equal 6.

That's according to the iPhone's new calculator, which behaves bizarrely and gives out results previously thought impossible using normal maths.

The strange animations that have been added to the iPhone calculator stop you actually using it to add up.

If you do the above calculation, for instance, you'll more often than not end up with a result like 24. That's because the animations that show when you press a button last so long – and you can't press another button until the animation.

Practically, that means that the phone will probably miss out the second add button, when you press it. Because the iPhone calculator doesn't register that press, it thinks that you've written 1 + 23, and gives you the correct result for that answer.

So there's nothing wrong with the iPhone's maths. But it's likely to make you think there's something wrong with yours: the slow, strange results could easily lead to getting things wrong, which might be worrying if you're using the numbers for something important.

To make sure that the iPhone's numbers are right, the best thing is to wait until the animation has faded and press the button again, while at the same time making sure the number has appeared in the read-out at the top. (There are also other calculator apps, like PCalc, available in the App Store.)

A number of Apple commentators have pointed out the problem, and a bug has been filed in Apple's internal bug reporting system.

The change appears to have been introduced with iOS 11, the new operating system that came out with the iPhone 8 in September. That brings with it a range of other – less perplexing – hidden features, which can be found here.