Sixth and seventh grade are using a basic four function calculator as this is what will be allowed for state testing. It would be helpful to have access to a calculator as all teachers allow them for homework most times as long as work is shown. (Students should show work for homework by writing down anything entered on a calculator and the answers.) In eighth grade, students will be using a scientific calculator. They are available in school. It is possible to find one on the computer, phone, or tablet so there is no need to purchase one.
To compute with fractions online (to check homework), google "fraction calculator" or try this:
This one has a fraction bar in the upper right corner:
Here's info about an app for the iphone: