Scale 1:25 or 1:75 why scale ruler first reading is 0.5m and 1m respectively ?

[zillah]

Dear folks

Simple question

Yes I do understand scale ration 1:25 means 1 unit on a map equal to 25 units on a real and scale ration 1:75 means 1 unit on a map equal to 75 units on real

Question my Kent tri scale ruler showing first number for ratio 1:25 as 0.5 m (i.e 50 cm, 500 mm) while first reading for ratio 1:75 as 1 m (100 cm, 1000mm) ?

My confusion for the ratio 1:25 ruler has 25 small tiny line between 0 and next reading means 25 units right ?? if I multiply 25*25 = 625 why scale reads it as 500 mm or 0.5 m????

Same thing for the ratio 1:75 ruler has 20 small tiny lines between 0 and next reading means 20 units right ?? if I multiply 20*75 = 1500 why do I have 1000 mm or 1 m ????

Thank

 

[3DDave]

The scale is marked.

If there are 25 divisions in 500mm then each small division represents 20mm.
If there are 20 divisions in 1000mm then each small division represents 50mm.

 

[hokie66]

The 50 on the 1:25 scale is just an intermediate, and it represents 500 mm. 50 occurs between each metre just for convenience. On this scale, each small division represents 2 mm, and each longer bar represents 10 mm.

On the 1:75 scale, the intermediate is not numbered, but it is there at, again, 500 mm. The 1, 2, 3, etc are metres, and each small division is 5 mm.

You just have to use the scales to get a feel for the divisions.

 

[cvg]

they are all different. my Alvin metric scale has 100, 200, 250, 300, 400, and 500 and does not have 25 or 75. all starting with 0.