Let’s convert each of these numbers into fractions:

1. 54

   • As a fraction:
     $54 = \frac{54}{1}$

2. -87

   • As a fraction:
     $-87 = \frac{-87}{1}$

3. 0.\overline{53} (Repeating 53)

   • Let $x = 0.\overline{53}$.
   • Multiply both sides by 100 to shift the decimal:
     $100x = 53.\overline{53}$
   • Subtract the original equation:
     $100x - x = 53.\overline{53} - 0.\overline{53}$
     $99x = 53$
   • Solve for $x$:
     $x = \frac{53}{99}$

4. 4.666… (Repeating 6)

   • Let $y = 4.\overline{6}$.
   • Multiply by 10 to shift the repeating part:
     $10y = 46.\overline{6}$
   • Subtract the original equation:
     $10y - y = 46.\overline{6} - 4.\overline{6}$
     $9y = 42$
   • Solve for $y$:
     $y = \frac{42}{9} = \frac{14}{3}$

5. 0.639

   • Since the decimal terminates, express it as a fraction over a power of 10:
     $0.639 = \frac{639}{1000}$
   • This fraction is already in simplest form since 639 and 1000 have no common factors.

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Would you like any of these solutions explained in more detail?

Here are five related questions for further exploration:

1. How can repeating decimals always be converted into fractions?
2. How do you determine the simplest form of a fraction?
3. Why does a terminating decimal always convert to a fraction with a power of 10 in the denominator?
4. What are some methods to convert improper fractions back to decimals?
5. How do mixed fractions differ from improper fractions?

Tip: A repeating decimal will always convert to a fraction with a denominator involving factors of 9.