Envision Math 2.0: Grade 8, Volume 1
EM
Envision Math 2.0: Grade 8, Volume 1 View details
1. Rational Numbers as Decimals
Continue to next subchapter

Exercise 1 Page 10

Remember that we want to begin by assigning a variable to represent the repeating decimal.

See solution.

Practice makes perfect

We are asked how we can write a repeating decimal as a fraction. To write repeating decimals as fractions, we need to follow a few steps.

  • Step 1. Assign a variable to represent the repeating decimal.
  • Step 2. Write an equation to equate the variable and the decimal.
  • Step 3. Multiply each side of the equation by 10^d, where d is the number of repeating digits in the repeating decimal.
  • Step 4. Subtract equivalent expressions of the variable and the repeating decimal from each side of the equation.
  • Step 5. Solve for the variable. Write an equivalent fraction so that the numerator and denominator are integers, if necessary.
Let's take a look at an example. We will consider a repeating decimal 5.43 and assign variable x to it. x = 5.43 Now we will multiply each side of the equation by 10^d, where d is the number of repeating digits in the repeating decimal. Since d=1 in our example, we will multiply both sides of our equation by 10. 10x = 54.3 Next, we will subtract equivalent expressions of the variable and the repeating decimal from each side of the equation. In our case, we will subtract x from the left-hand side and 5.43 from the right-hand side. 10x - x = 54.3 - 5.43 Let's solve this equation for x!
10x - x = 54.3 - 5.43
9x = 48.87
90x = 489
x = 489/90
We found that the repeating decimal 5.43 can be rewritten as a fraction as 48990. This can also be written as 16330, or 5 1330.