write \\frac{9}{20} as a decimal number.

Explanation:

Step1: Convert the denominator to 100

Multiply numerator and denominator by 5. $$\frac{9\times5}{20\times5}=\frac{45}{100}$$

Step2: Write as decimal

Since $\frac{45}{100}=45\div100$, move the decimal point two places to the left. $$45\div100 = 0.45$$

Answer:

$0.45$