Explain How Compound Interest Works Against You on a Credit Card

Compound interest on a credit card is the only financial mechanism most people interact with daily and genuinely do not understand. This explains how it is calculated, what happens to a real balance over twelve months when you pay the minimum, why the balance grows even though you are paying, the inflection point where a higher payment changes the trajectory, and the rule that makes the maths intuitive.

Explain compound interest in credit card debt for someone who has heard the term but does not understand why paying the minimum is so damaging.

Cover:
1. How credit card interest is calculated in practice (daily rate, monthly application)
2. What happens when only the minimum payment is made: the concrete numbers over twelve months for a {BALANCE} balance at a typical UK APR
3. Why the balance grows even when you are paying every month
4. The inflection point: when the trajectory changes if you pay {HIGHER_PAYMENT} instead
5. One rule that makes the maths of credit card debt intuitively clear without needing a calculator

Under 300 words. Use concrete numbers.