# +1=1 became false between versions 8.5.5 and 8.5.10. How and why?

**URL:** <https://swi-prolog.discourse.group/t/1-1-became-false-between-versions-8-5-5-and-8-5-10-how-and-why/5883>\
**Category:** Help!\
**Created:** [October 21, 2022, 8:52am UTC](https://swi-prolog.discourse.group/t/1-1-became-false-between-versions-8-5-5-and-8-5-10-how-and-why/5883 "2022-10-21T08:52:51Z")\
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**Author:** ![jan](https://yyz2.discourse-cdn.com/free1/user_avatar/swi-prolog.discourse.group/jan/32/4_2.png) [@jan](https://swi-prolog.discourse.group/u/jan)\
**Post date:** [October 21, 2022, 9:18am UTC](https://swi-prolog.discourse.group/t/1-1-became-false-between-versions-8-5-5-and-8-5-10-how-and-why/5883/3 "2022-10-21T09:18:29Z")

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Alternatively, go to the download page ([SWI-Prolog downloads](https://www.swi-prolog.org/download/devel)) and follow the ChangeLog link. That gives a page with the latest release changelog and a menu that allows selecting a range of versions. Select 8.5.5 and 8.5.10 and search for + and you find

> [Jan 26 2022]
> 
> MODIFIED: Read +digits as a term rather than a number. This changes also removes the space when writing e.g. +42. Reading +digits as a number predates the ISO standard and current practice. It was in SWI-Prolog since version 2.5 …

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