If you’ve upgraded your iPhone’s operating system to iOS 11, try this: Go to the calculator app and quickly type 1+2+3. You likely won’t get 6.
You might get 23, or 24, or 16, or 32, or something else, depending on what buttons you tap and in what order, and, obviously, none of which is the right answer.
According to a group of eagle-eyed iPhone users on Reddit who spotted the issue, it seems to be because of a new animation in the calculator app, where a button briefly fades to white when you press it. The result is that if you press an operator button (i.e., the plus sign) before the short animation finishes, the app ignores it. So, 1 + 2 + 3 accidentally gets read as 1 + 23.
It’s not entirely clear why Apple would design its calculator like this, and whether the bug will be fixed. Apple wasn’t immediately available to comment, but it seems like another example of the company no longer sweating the details in its designs. For now, we should probably all be more patient in typing out our calculations.