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GCSE Mathematics · key term
The original amount borrowed or invested, before interest is added.
Used by AQA, Edexcel and OCR
Specification R9, R16 · Paper 1, Paper 2, Paper 3
The initial amount borrowed or invested on which interest is calculated.
Revise: PercentagesWith simple interest, every period’s interest is calculated from the original principal, rather than from a growing balance.
The amount originally invested or borrowed before interest is applied.
Check whether the question asks for simple interest alone or the total balance. For the total, add the interest to the principal.
Underline whether the question asks for the interest alone or the total amount. Add the principal only when the total is required.
For simple interest, always calculate each period’s interest from the original principal, not from a growing balance.
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Specification R9 · Paper 1, Paper 2, Paper 3
The original amount borrowed or invested, before any interest is added.
Revise: Simple Interest and Financial MathematicsThe original amount borrowed or invested is called the principal.
Specification 2.03c, 5.03a · Paper 1 (Foundation), Paper 2 (Foundation), Paper 3 (Foundation), Paper 4 (Higher), Paper 5 (Higher), Paper 6 (Higher)
The original sum of money invested or borrowed.
Revise: Percentage Change and InterestWith simple interest, each year's interest is calculated from the original principal. It does not earn interest on earlier interest, so the same amount is added each year.