Dear Williams 775,
Thankyou for your question.
What I am sending you here is a website which explains this process of reading a ruler.
This has metric and english ruler information and really helped me.
http://www.onlineconversion.com/faq_05.htm
If after reading you need more help just let me know please?
Sincerely,Don4U
home owner
Skilled in many areas,I work to meet your needs.