Find the simple interest (in ₹) on a sum of ₹3500 borrowed at a rate of…

Concept — Simple interest is charged only on the original sum borrowed, called the principal. Interest already earned is never added back to the principal, so the interest for every year of the term is exactly the same. For a principal P lent at R% per annum for T years, the simple interest is SI = (P × R × T) / 100.

Applying it here

1. Read off the three quantities the formula needs: principal P = ₹3500, rate R = 7% per annum, time T = 6 years.

2. Substitute them into the formula: SI = (3500 × 7 × 6) / 100.

3. Multiply the principal by the rate: 3500 × 7 = 24500.

4. Multiply that product by the number of years: 24500 × 6 = 147000.

5. Divide by 100 to undo the percentage: 147000 / 100 = 1470.

Cross-check

Rebuild the figure one year at a time. In a single year the interest is 7% of ₹3500, that is ₹245. Because simple interest repeats unchanged every year, six years give 245 × 6 = ₹1470, which matches the formula.

It also helps to see what simple interest is not. Had the interest been compounded, each year's interest would be calculated on a balance that keeps growing, so the six-year total would come out higher than ₹1470. The word “simple” is exactly what keeps the base fixed at ₹3500 for all six years.

So the simple interest on ₹3500 at 7% per annum for 6 years is ₹1470.