The decimal number 2.25 can be converted into a fraction as follows:

$2.25 = \frac{9}{4}$

Here's how it's done:

1. Write the decimal as a fraction:
   $2.25 = \frac{225}{100}$

2. Simplify the fraction:
   Find the greatest common divisor (GCD) of 225 and 100, which is 25, and divide both the numerator and the denominator by it. $\frac{225 \div 25}{100 \div 25} = \frac{9}{4}$

So, 2.25 is equivalent to $\frac{9}{4}$ as a fraction.

Would you like more details or have any questions?

Here are some related questions:

1. How do you convert a repeating decimal to a fraction?
2. What is the fraction equivalent of 2.5?
3. How can you convert 1.75 into a fraction?
4. What is the decimal form of $\frac{7}{4}$?
5. How do you simplify a fraction?

Tip: When converting decimals to fractions, remember that moving the decimal point corresponds to multiplying by powers of 10.