Question: I’m trying to calculate what percentage is 30 out of 40. How do I do that?

MathBlog: A percent tells us how many parts out of 100 something is. To write a percent as a fraction, just remove the percent symbol and write the number over 100 as the denominator. Below we explain what is 30 out of 40 in percentage, and how you calculate it.

What is 30/40 in percentage?

Answer: 30 is 75% out of 40.

We have two methods to figure it out, with steps for easy understanding.

Method 1: Long division with remainder

Calculate \( 30:40 \)

  1. 40 enters into 30, 0 times, remainder 30
    Result (ongoing) = 0.
    Multiply the remainder by 10 to get 300. Now calculate 300 : 40
  2. 40 enters into 300, 7 times, remainder 20
    Result (ongoing) = 0.7
    Multiply the remainder by 10 to get 200. Now calculate 200 : 40
  3. 40 enters into 200, 5 times, remainder 0
    Remainder = 0, means you're done.
    Result (final) = 0.75

Now you multiply the reults by 100 \( (0.75 \times 100 = 75 ) \) and you get 75%.

Solution: 30 out of 40 equals 75%.

Method 2: Using fractions

Calculate \( P(\text{%}) = \frac{ 30 }{ 40 } \times 100 \)

  1. We need to get the fraction to be of the type \( \frac{ P }{ 100 } \times 100 \)

  2. In our case we need \( \frac { 30 \times x }{ 40 \times x } \times 100 \)

    That means \( 40 \times x = 100 \)

    \( x = \frac{100}{ 40 } = 2.5 \)

  3. Our fraction is now \( \frac { 30 \times 2.5 }{ 40 \times 2.5 } \times 100 \)

  4. We know that the denominator \( 40 \times 2.5 = 100 \) so we construct the fraction again.

    \( P = \frac { 30 \times 2.5 }{100} \times 100 \)
    \(= 30 \times 2.5 \)

  5. Since \( 30 \times 2.5 = 75 \), we have our result
    \( P = 75 \).

Solution: 30 out of 40 equals 75%.

Calculate other numbers

Calculate percentage of two numbers