Java Script Required for calculated fields

Good Day

I need some help with code please.

I have built a system for a client in Microsoft Dynamics CRM, we have a customer portal addon, however, on the portal page i would like to add two calculated fields which basically does conversions, for example

1.
Amount HASH Rate
$1000 10 TH/s

The amount is entered by the user and the result is returned by the code. (HASH Rate = (Amount / 100)

2.
1.
Amount HASH Rate
$270 10 TH/s

The amount is entered by the user and the result is returned by the code. (HASH Rate = (Amount / 27)

So basically i need the code to add to the webpage in three different places to do these calculations

Can anyone assist please?