creator formula for lookup value

creator formula for lookup value

I am using zoho creator and doing some really cool things with the formulas, one thing i am stuck on in creating a field with a number from data I have added, for example, my input field value would be something like " 54" - 1372mm" but i would like a filed to look at this and automatically enter "1.372" also it would need to also be able to convert " 30" - 762mm" to give a response of "0.762" ... many thanks for looking at my post :)