Method for correcting the number display?

I use line for Vehicle Speed but display values ​​less where the value is units Individual

value targetId=“64” units=“km/h” offset=“4” length=“1”

When using the following conversion formula, the numbers jump without sequence, knowing that they are identical to the GPS speed.

value targetId=“64” units=“km/h” offset=“4” length=“1” conversion=“V*2.7”

What is the method for smoothing and correcting the display of numbers smoothly?