精度 and 桁: measurement quality and displayed digits
Distinguish checking measurement quality from displaying more digits. More decimal places alone do not establish an improvement in 精度.
Read 精度 with the measurement method
精度, read せいど, can refer to precision or accuracy. 新しい定規で測定の精度が上がった。 says that a new ruler improved the measurement’s 精度.
The sentence describes the 精度 of a measurement made with the new ruler. Distinguish the measuring instrument and conditions from the format used to display the result.
桁 describes numerical positions
桁, read けた, refers here to a digit position or number of digits. The forms 100 and 100.00 display different numbers of decimal places but have the same numerical value.
If only the display format of the same measurement changes from 100 to 100.00, the measuring instrument and process have not changed. Extra displayed digits alone do not describe a new measurement.
Distinguish testing from formatting
模型の動きを何度も試して精度を確かめた。 says that someone tested the model’s movement repeatedly and checked its 精度. An actual testing method is provided here.
Look for measurement or testing evidence when assessing 精度. A longer numerical display does not by itself supply that evidence.
Does displaying 100 centimeters as 100.00 centimeters necessarily improve the measurement’s 精度?
Show the answer and why
No. The display can contain more digits while the measurement method stays the same. Check measurement or testing evidence for an actual improvement.