Final answer:
The least number among 15, 0.51, and 15% is 0.15. The conversion of 15% to decimal form is 0.15, and 0.51 is already in decimal form. We compare these values as decimals to find the smallest.
Step-by-step explanation:
When comparing numbers, including decimals and percentages, to determine which number is the least, we should evaluate them in the same form. Starting with the number 0.51, it is already in decimal form, so we do not need to change anything. The number 0.15 is also a decimal; this is clearly smaller than 0.51 because it has a lesser value in the tenths place (1 is less than 5).
When converting percentages to decimals, we remember that a percent can be written as a fraction over 100. Therefore, 15% becomes 15/100, which is 0.15 in decimal form. The three decimal numbers we are comparing are 15 (which can be thought of as 15.0 to compare as a decimal), 0.51, and 0.15. Out of these, 0.15, which is also 15% converted into a decimal, is the smallest.
Let's summarize the conversion of each given value into decimal form:
- 0.51 is already in decimal form.
- 0.15 is the decimal form of 15%.
Therefore, the least number among 15, 0.51, and 15% is 0.15.