How could I work out my monthly mortgage payments if I only had a pen and paper?

I know I could use a simple mortgage calculator, but I am curious to know how my mortgage payment is arrived at. Is it cumulative interest plus principal divided by years and months. Please could you supply a detailed example as I not too hot with maths. For example a £100000 mortgage at 5% over 25 years.

What is a VPN?

VPN is (Virtual Private Network) were first used by companies to enable their employees to securely access internal systems such as email remotely (e.g. from home or while on business trips). Today they are increasingly being used for personal use by individuals to protect their privacy while online in public places (e.g. when using the wi-fi connection in a cafe) or in a country where the internet is censored / blocked (e.g. China, Saudi Arabia…).