01 Key Concepts
Principal (P)
The original amount of money borrowed or invested.
Rate (R)
The interest rate per year, usually given as a percentage.
Time (T)
The duration of the loan or investment, usually in years.
Simple Interest Formula
SI = (P x R x T) / 100.
Amount
The total amount after interest is added: Amount = Principal + Simple Interest.
03 Key Formulas
- SI = (P x R x T) / 100
- Amount = P + SI
04 Solved Examples
Example 1 Find the simple interest on $2,000 at 5% per year for 3 years.
- SI = (P x R x T)/100 = (2000 x 5 x 3)/100.
- = 30000/100.
Answer: $300
Example 2 Find the total amount for the previous example.
- Amount = P + SI = 2000 + 300.
Answer: $2,300
Example 3 At what rate will $1,500 earn $180 interest in 2 years?
- SI = (P x R x T)/100, so 180 = (1500 x R x 2)/100.
- 180 = 30R.
- R = 180/30.
Answer: 6% per year
05 Practice Questions
1Find SI on $1,000 at 4% for 2 years.
$80
2Find SI on $5,000 at 6% for 1 year.
$300
3Find the amount for $3,000 at 5% for 4 years.
$3,600
4Find the rate if $2,000 earns $400 SI in 5 years.
4%
5Find the time if $1,200 at 10% earns $360 SI.
3 years
📄 Simple Interest — Downloadable Worksheet
10 questions with a full answer key. Grab the PDF to print, or try the interactive version in your browser.