Fractions Toolkit
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Notas de aula
Basic Fractions
- A fraction is written as \frac{a}{b} where a (numerator) and b (denominator) are integers.
- The denominator shows how many parts each whole is split into; the numerator shows how many parts you have.
- A fraction is less than 1 if numerator < denominator; greater than 1 if numerator > denominator.
- To find a fraction of an amount: divide by denominator, multiply by numerator (e.g., \frac{2}{5} of 60: 60 ÷ 5 = 12, 12 × 2 = 24).
- Equivalent fractions represent the same amount; multiply top and bottom by the same number to find them.
- Simplify a fraction by dividing numerator and denominator by a common factor (e.g., \frac{12}{18} = \frac{2}{3}).
Mixed Numbers & Improper Fractions
- A mixed number has an integer part and a fraction part (e.g., 3\frac{3}{4}).
- An improper fraction (top-heavy) has numerator ≥ denominator (e.g., \frac{15}{4}).
- To convert a mixed number to an improper fraction: multiply the whole number by the denominator, add the numerator, write over the denominator.
- To convert an improper fraction to a mixed number: divide numerator by denominator; the quotient is the whole number, remainder over denominator is the fraction.
- Always convert mixed numbers to improper fractions before adding, subtracting, multiplying, or dividing.
Adding & Subtracting Fractions
- Find the lowest common denominator (LCD) of the fractions.
- Rewrite each fraction as an equivalent fraction with the LCD.
- Add or subtract the numerators; keep the denominator the same.
- Simplify the result by cancelling common factors.
- If mixed numbers are involved, convert them to improper fractions first, then add/subtract, and convert back if needed.
Multiplying Fractions
- Cancel any common factors between numerators and denominators before multiplying.
- Multiply the numerators together and the denominators together.
- Simplify the resulting fraction if possible.
- If a mixed number is involved, convert it to an improper fraction first.
- Example: \frac{4}{15} \times \frac{25}{11} = \frac{4 \times 25}{15 \times 11} = \frac{100}{165} = \frac{20}{33} after cancelling.
Dividing Fractions
- To divide, flip the second fraction (find its reciprocal) and change ÷ to ×.
- Then follow the multiplication steps: cancel, multiply numerators, multiply denominators.
- If a mixed number is involved, convert it to an improper fraction first.
- Example: 3\frac{1}{4} \div \frac{3}{8} = \frac{13}{4} \times \frac{8}{3} = \frac{13 \times 8}{4 \times 3} = \frac{104}{12} = \frac{26}{3} = 8\frac{2}{3}.
Working with Fractions of Amounts
- To find a fraction of an amount, multiply the amount by the fraction.
- Write the amount as a fraction over 1 (e.g., 60 = \frac{60}{1}).
- Then multiply the fractions as usual.
- Alternatively, divide by denominator then multiply by numerator.
Simplifying Fractions
- A fraction is in its simplest form when numerator and denominator have no common factors other than 1.
- Divide both numerator and denominator by their highest common factor (HCF).
- Your calculator can simplify fractions automatically, but show the factor you divided by if working is required.
Common Mistakes & Tips
- When adding/subtracting, do not add denominators.
- Always simplify final answers unless stated otherwise.
- Convert mixed numbers to improper fractions before any operation.
- Remember "flip'n'times" for division: flip the second fraction and multiply.
Slides
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Questões de prática
Prévia grátis — 8 de 56 perguntas. Cadastre-se para ver todas.
1.What is a fraction?
Easy- AA number written as a/b where a and b are integers
- BA number with a decimal point
- CA number less than 1
- DA number greater than 1
2.What is the numerator in the fraction 3/5?
Easy- A3
- B5
- C8
- D2
3.Which of the following is an improper fraction?
Easy- A7/4
- B3/5
- C2/3
- D1/2
4.Convert 5 2/7 into an improper fraction.
Easy- A37/7
- B35/7
- C12/7
- D33/7
5.Convert 22/3 into a mixed number.
Easy- A7 1/3
- B7 2/3
- C6 1/3
- D7 1/2
6.Simplify 12/18 to its lowest terms.
Easy- A2/3
- B3/4
- C1/2
- D4/6
7.Work out 2/5 of 60.
Easy- A24
- B12
- C30
- D150
8.Which fraction is equivalent to 3.875?
Medium- A31/8
- B15/4
- C29/8
- D15/8
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