Simple website to be build with 5 calculators

Description

Hi all,
I am looking to have a simple website build, see my other websites www.ianhalfpenny.co.uk and www.thebranteffect.com but I also want to add 5 different calculators on the site. I have attached sample URL's so you can see the calculators. I'd like you, the programmer, to work out the calculations and formula's using the URL's provided. I can help with the formula for number 3, that doesn't have a sample URL to look to.
If you don't understand the formula's or the calculations then this project isn't for you.
I want
1. Compound Interest Calculatorhttps://www.thecalculatorsite.com/finance/calculators/compoundinterestcalculator.php
2. Pension Cost comparison Calculatorhttps://www.candidmoney.com/calculators/pension-cost-comparison-calculator
3. Pension calculator - showing the impact of broker fees.We need to build this ourselves.
4. An interest only mortgage calculator (a very simple one)https://www.halifax.co.uk/mortgages/existing-customers/mortgage-support/interest-only-payments/calculate.html
5. A mortgage overpayment calculator (again, very simple and easy to find one)https://www.halifax.co.uk/mortgages/mortgage-calculator/overpayment-calculator.html
My budget is a guide. Please send your proposal and price for my consideration.
Thanks.