The fraction allows you to communicate length and tolerance in a single number. A decimal implies precision to the last number, a measure with a fraction can show 1/8 as more granular than 1/16. 1/8 of a cm is less precise than a mm, but if you wrote 1.125 cm, you are now implying sub mm level precision.
This matters because the level needed in building generally doesn’t line up to 1/10 measurements. For example if you had a brick wall and a row had 1 cm height differences between bricks in a row it would be extremely obvious and look terrible. A 1mm height difference would be impossible to notice, but is also overkill to get that level. Ideal is about 5/8 cm or 6.35 mm difference over 3 meters of wall. The fractional measure often ends up easier to work with in practice.
“The fraction allows you to communicate length and tolerance in a single number”
I don’t see how that isn’t true of decimals, too. 0.1 indicates a precision of 1 digit, 0.12 indicates a precision of 2, 0.120 indicates a precision of three.
The fraction allows you to communicate length and tolerance in a single number. A decimal implies precision to the last number, a measure with a fraction can show 1/8 as more granular than 1/16. 1/8 of a cm is less precise than a mm, but if you wrote 1.125 cm, you are now implying sub mm level precision.
This matters because the level needed in building generally doesn’t line up to 1/10 measurements. For example if you had a brick wall and a row had 1 cm height differences between bricks in a row it would be extremely obvious and look terrible. A 1mm height difference would be impossible to notice, but is also overkill to get that level. Ideal is about 5/8 cm or 6.35 mm difference over 3 meters of wall. The fractional measure often ends up easier to work with in practice.
I don’t see how that isn’t true of decimals, too. 0.1 indicates a precision of 1 digit, 0.12 indicates a precision of 2, 0.120 indicates a precision of three.