Amanda needs to write the number thirteen and thirty-one hundredths as a decimal.

In mathematical terms:

• "Thirteen" is the whole number part: 13
• "Thirty-one hundredths" means 31 over 100, which is 0.31

So, the number Amanda is trying to write is 13.31.

The correct answer is C.

Would you like more details or have any other questions?

Here are 5 related questions to explore:

1. What is the place value of digits in a decimal number?
2. How do you convert fractions to decimals?
3. What are the differences between hundredths, thousandths, and ten-thousandths places?
4. How can you express a decimal as a fraction?
5. What are some common uses of decimals in real life?

Tip: Always align decimal places when adding or subtracting decimals to ensure accuracy.