Imagine a tape measure which could react to voice commands.
Today’s invention is a measure which has an internal drive motor and a processor capable of interpreting a small number of spoken words.
This allows the user to say “12.3cm” and have the correct length of tape emerge.
You could also say “one third of that” and have the tape length reduce to 4.1cm at once.
It might also be possible to have the device announce the current length of the extended tape (in any units required).