Using calculus to convert marks to percentages

I am having trouble doing a probably very basic thing! The tests I give student are usually /15 or /25 etc, so I have set up grade types in this way - e.g. numeric, max grade value of 25, mimumum grade value 0, threshold value 0. However when I try to concert them to % using calculus, I get e.g. 0.70% instead of 70%. What am I doing wrong?

On another note, many thanks for answering the last query - very quick and helpful

Hi Corina,
Would you mind sending me a screenshot of the calculus configured for that last column?
An image when arrows are on screen would be great, I'll give it a look and reply you back with the solution.
Thanks