If entering over the sidebar "Division (wideslash)" you get "{<?>} wideslash {<?>}" (with {} around the placeholders) else if entering "Division (counter wideslash)" you get "<?> widebslash <?>" (without {} around the placeholders). This both should be consistent and I think the one with {} around the placeholders should be prefered.
Confirmed the binary operator strings are composed inconsistently into the formula editor when entering Division binary operators from the "Elements" sidebar.
Takeshi Abe committed a patch related to this issue. It has been pushed to "master": http://cgit.freedesktop.org/libreoffice/core/commit/?id=239b662753bee4148cac51268cb203c7527036be tdf#102007 Surround widebslash's placeholders with braces It will be available in 5.3.0. The patch should be included in the daily builds available at http://dev-builds.libreoffice.org/daily/ in the next 24-48 hours. More information about daily builds can be found at: http://wiki.documentfoundation.org/Testing_Daily_Builds Affected users are encouraged to test the fix and report feedback.