Looking for a plugin/widget

Hi Everyone,

I have been searching for days for a suitable plugin/widget for my site. I am looking for a calculator/generator plugin in which a user picks from a drop down list and another field is automatically generated with an answer. Similar to this IVF Calculator on Spire website http://www.spirehealthcare.com/ivf-scotland/about-us/success-rates.

Thanks in advance.
Jenn