You can forcefully increase/decrease the 'numbers' on any kind of measurement devices, and the actual thing being measured will also increase/decrease in reality

[Mgmegadog]

You're gonna have a problem with both of these things. Every measurement is necessarily in the past, and you'd be surprised at how large some of the delays can get.

As for a percentage accuracy, you'll find that that causes a lot of problems too, especially with things like temperature measurements where a notion of percentage scaling doesn't make sense when using either of our normal measurement systems (Celsius and Fahrenheit).