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If You Type 1+2+3 Into Your iPhone's Calculator on iOS 11, You Probably Won't Get 6 (qz.com)

Posted by msmash on from the great-software dept.

A reader shares a report: 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. 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.

3 of 337 comments (clear)

  1. First CS assignment. by Anonymous Coward · · Score: 5, Informative

    After a basic hello world intro, I had to write a calculator to add subtract multiply and divide in the first week of college. Had mine worked like apples Iâ(TM)d have likely failed. How does this happen?

    1. Re:First CS assignment. by nine-times · · Score: 5, Informative

      How does this happen?

      It explains how it happened in the summary:

      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 doing math wrong. It does a brief animation when you press a button, and it doesn't necessarily read the next button you press while the animation is happening. Therefore, if you press the calculator buttons too quickly, it won't register all the things you pressed. Based on the buttons you do press, it does the math correctly.

      So if you press "1+2+3" it might miss the second "+" and register "1+23" and give you "24" as an answer.

  2. Re:Windows Calculator by Obfuscant · · Score: 5, Informative

    How strange.

    Not strange at all. That is zero within "eps", and is because they are using the Intel or AMD math processor for the square root. WE look at "4" and know the square root is exactly two because we learned that. The CPU goes through a standard algorithm for determining the square root of a number, and because of the inherent imprecision of floating point math with a limited number of bits, the answer is not identical to zero because the square root of 4 is not identical to 2.