What is 12.100101... as a Fraction?

12.1001 equals 1197919900 as a fraction.

How do you turn 12.1001 repeating into a fraction?

Detailed Answer:

Step 1: To convert 12.1001 repeating into a fraction, begin writing this simple equation:

n = 12.1001 (equation 1)

Step 2: Notice that there are 2 digits in the repeating block (01) and 2 digits in the non-repeating part (10). Multiply both sides by 10⁴ = 10000.

10000 × n = 121001.01 (equation 2)

Step 3: Now subtract equation 1 from equation 2 to cancel the repeating block (or repetend) out.

10000 × n = 121001.01
  100 × n = 12.1001
 9900 × n = 119791

n = 1197919900 (answer)

12.1001 = 1197919900 as the lowest possible fraction.

As the numerator is greater than the denominator, we have an improper fraction, so we can also express it as a mixed number, thus 1197919900 is also equal to 129919900 when expressed as a mixed number.

The repeating decimal 12.1001 (vinculum notation) has a repeated block length of 2. It is also represented as 12.10010101... (ellipsis notation) which equals approximately 12.100101010101 (decimal approximation)(*).

The recurring decimal 12.1001 can be written as a ratio of two integers having 119791 as the numerator and 9900 as the denominator. So, it is a rational number (named after ratio). It can be shown that a number is rational if its decimal representation is repeating or terminating.

(*) At present, there is no single universally accepted notation or phrasing for repeating decimals.