Convert .454545454545......(repeating decimal) to a rational number in simplest form.

1 answer

Let \( x = 0.4545454545\ldots \).

To convert this repeating decimal to a fraction, we first observe the repeated part, which is "45". This consists of two digits.

To eliminate the repeating decimal, we can multiply \( x \) by 100 (since there are two digits that repeat):

\[ 100x = 45.4545454545\ldots \]

Now, we can set up an equation using the original \( x \):

\[ x = 0.4545454545\ldots \] \[ 100x = 45.4545454545\ldots \]

Next, we subtract the first equation from the second:

\[ 100x - x = 45.4545454545\ldots - 0.4545454545\ldots \]

This simplifies to:

\[ 99x = 45 \]

Now, solve for \( x \):

\[ x = \frac{45}{99} \]

Next, we simplify the fraction \( \frac{45}{99} \). The greatest common divisor (GCD) of 45 and 99 can be found. The prime factorization of both numbers is:

  • \( 45 = 3^2 \times 5 \)
  • \( 99 = 3^2 \times 11 \)

The GCD is \( 3^2 = 9 \).

Now, we divide both the numerator and the denominator by their GCD (9):

\[ \frac{45 \div 9}{99 \div 9} = \frac{5}{11} \]

Thus, the decimal \( 0.4545454545\ldots \) can be expressed as the fraction:

\[ \boxed{\frac{5}{11}} \]