OpenRevise

Flashcards · Maths · Number Without a Calculator

Fractions

17 cards

  1. How do you simplify a fraction?

    Divide the top and bottom by their highest common factor, so \(\dfrac{36}{48} = \dfrac{3}{4}\).

  2. Write \(3\dfrac{2}{5}\) as an improper fraction.

    \(3 \times 5 + 2 = 17\), so \(\dfrac{17}{5}\).

  3. How do you work out \(\dfrac{3}{4} + \dfrac{5}{6}\)?

    Use a common denominator of 12: \(\dfrac{9}{12} + \dfrac{10}{12} = \dfrac{19}{12} = 1\dfrac{7}{12}\).

  4. What happens to the denominator when you add fractions?

    It stays the same. Only the numerators are added, and the denominators are never added.

  5. How do you multiply fractions?

    Multiply the numerators, multiply the denominators, and cancel first if you can.

  6. What is \(\dfrac{3}{4} \times \dfrac{2}{3}\)?

    \(\dfrac{6}{12} = \dfrac{1}{2}\).

  7. How do you divide by a fraction?

    Keep, change, flip: \(\dfrac{2}{3} \div \dfrac{4}{5} = \dfrac{2}{3} \times \dfrac{5}{4} = \dfrac{5}{6}\).

  8. What must you do to mixed numbers before multiplying or dividing?

    Turn them into improper fractions.

  9. How do you find \(\dfrac{3}{5}\) of 80?

    Divide by the denominator (\(80 \div 5 = 16\)), then multiply by the numerator (\(16 \times 3 = 48\)).

  10. What is the reciprocal of \(\dfrac{5}{7}\)?

    \(\dfrac{7}{5}\).

  11. How do you write 35 minutes as a fraction of 2 hours?

    Use the same units first: \(\dfrac{35}{120} = \dfrac{7}{24}\).

  12. \(\dfrac{3}{5}\) of a number is 36. What is the number?

    \(36 \div 3 = 12\) is one fifth, so the number is \(12 \times 5 = 60\).

  13. What is \(6 \div \dfrac{2}{3}\)?

    9. Write 6 as \(\dfrac{6}{1}\) and flip: \(\dfrac{6}{1} \times \dfrac{3}{2} = 9\).

  14. How do you work out \(3\dfrac{1}{3} - 1\dfrac{3}{4}\)?

    Improper fractions \(\dfrac{10}{3} - \dfrac{7}{4} = \dfrac{40}{12} - \dfrac{21}{12} = \dfrac{19}{12} = 1\dfrac{7}{12}\).

  15. What is the common mistake with \(\dfrac{1}{2} + \dfrac{1}{3}\)?

    Adding tops and bottoms to get \(\dfrac{2}{5}\). The correct answer is \(\dfrac{3}{6} + \dfrac{2}{6} = \dfrac{5}{6}\).

  16. Which fraction operations need a common denominator?

    Adding and subtracting only. Multiplying and dividing do not.

  17. How do you compare \(\dfrac{5}{8}\) and \(\dfrac{3}{5}\)?

    Use a common denominator of 40: \(\dfrac{25}{40}\) and \(\dfrac{24}{40}\), so \(\dfrac{5}{8}\) is larger.