Optional Mathematics is generally introduced in Grade 9. However many curriculum- and textbook developers working with private publications have worked very hard to introduce optional mathematics right from grade 8 / class 8. In Nepal, it is popularly called Opt. Maths or Optional Maths.
Shubharambha Publication has kept the link of flipbook version of Class 8 Optional Mathematics in their website. We have hereby share the link for your convenience. Please follow the box below for the book overview and further below to access the flipbook. It is however very comfortable to have paper version of any textbooks. Flipbooks have been getting popular especially for teachers to use in online teaching.
Disclaimer: Please comment below if any of these links are not taking you to the required resource.