What Percentage of 40 Is 30? Simple Answer and Method
30 is 75% of 40. You find this by dividing the part (30) by the whole (40) and multiplying by 100, which gives 0.75 × 100 = 75%.
How the Calculation Works
The core formula for any “what percent” question is:
Percentage = (Part ÷ Whole) × 100
Here, the part is 30 and the whole is 40:
- 30 ÷ 40 = 0.75
- 0.75 × 100 = 75
The decimal 0.75 means 30 occupies three-quarters of 40, and three-quarters as a percent is 75%. A quick sanity check: 75% is the same as 3/4. Since 40 ÷ 4 = 10, one quarter of 40 is 10, and three quarters is 30.
Quick Example
Suppose a class has 40 students and 30 passed an exam. What percentage passed?
(30 ÷ 40) × 100 = 75%
So 75% of the class passed, and the remaining 25% (10 students) did not.
The same method works for any similar problem: divide the part by the whole, then multiply by 100. A result over 100% simply means the part was larger than the whole, which happens with growth or increases.
Why the Order Matters
A common mistake is flipping the numbers and dividing 40 by 30, which gives about 133%. That answer is only correct if the question were reversed — “what percentage of 30 is 40?” When the phrase is “of 40,” then 40 is the base, and the other number sits on top as the part.
Key Takeaways
- 30 is 75% of 40, found by dividing 30 by 40 and multiplying by 100.
- The formula is Percentage = (Part ÷ Whole) × 100.
- 30/40 simplifies to 3/4, and 3/4 equals 75%.
- To verify, remember that 25% of 40 is 10, so 75% must be 30.
