What if you get a new ruler that’s 4 times as precise than the one you have that measures to 0.1cm? You don’t want to record it as 0.70cm, because that’s more precise than your measurement. But you could record it in 40ths with fractions.
Another way to look at it is that decimal is already a fractional system (1/10, 1/100, 1/1000) that doesn’t allow you to use 90% of possible fractions.
If there’s a technical need you can have your scale divided into whatever you want. There’s nothing preventing you into dividing your scale every 0.25mm to get 1/4th precision. It’s very rarely done because there’s no need, but it’s absolutely possible.
Thermometers have sometimes division per 0.5°C instead of 1°C
What if you get a new ruler that’s 4 times as precise than the one you have that measures to 0.1cm? You don’t want to record it as 0.70cm, because that’s more precise than your measurement. But you could record it in 40ths with fractions.
Another way to look at it is that decimal is already a fractional system (1/10, 1/100, 1/1000) that doesn’t allow you to use 90% of possible fractions.
If there’s a technical need you can have your scale divided into whatever you want. There’s nothing preventing you into dividing your scale every 0.25mm to get 1/4th precision. It’s very rarely done because there’s no need, but it’s absolutely possible.
Thermometers have sometimes division per 0.5°C instead of 1°C