The number 9 is 20% of what number?

To determine the number for which 9 is 20%, you can set up the equation based on the relationship between part, whole, and percentage. The formula to find the whole number when you know the part and the percentage is to divide the part by the percentage expressed as a decimal.

First, recognize that 20% can be converted to a decimal which is 0.20. The question implies:

9 = 0.20 * X

To find X (the whole number), you can rearrange the equation:

X = 9 / 0.20

Now perform the division:

X = 9 ÷ 0.20 = 9 ÷ (20/100) = 9 * (100/20) = 9 * 5 = 45.

Thus, when you calculate this, you find that the number is 45. Therefore, since 20% of 45 is equal to 9, the correct answer aligns with the understanding of percentage calculations and conversions, confirming that the answer is indeed 45.