The math operations will only happen to numbers (via the SNMP return type). The inclusion of a ; means it is returning as a string.
You might try using the [UPS-MIB OIDs](http://www.oidview.com/mibs/0/UPS-MIB.html) and see if the frequency endpoint there returns a cleaner value first. That's just bad/lazy MIB design that defeats the purpose of SNMP. -- You are receiving this because you are subscribed to this thread. Reply to this email directly or view it on GitHub: https://github.com/monitoring-plugins/monitoring-plugins/pull/1417#issuecomment-244744038
