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Math Guide

Fraction Calculator Guide: All 4 Operations Explained

Fractions are used in cooking, measurements, probability, and algebra. Here are the clear, step-by-step methods for all four arithmetic operations with fractions.

Fraction Operations at a Glance

Addition / Subtraction

Find LCD → convert → add/subtract numerators → simplify
1/4 + 1/6 → LCD=12 → 3/12 + 2/12 = 5/12

Multiplication

Multiply numerators × numerators, denominators × denominators → simplify
3/4 × 2/5 = 6/20 = 3/10

Division

Flip second fraction, then multiply
3/4 ÷ 2/3 = 3/4 × 3/2 = 9/8 = 1 1/8

Finding the LCD (Least Common Denominator)

The LCD of two denominators is their Least Common Multiple (LCM). To find LCM:

Find LCD of 4 and 6:
Multiples of 4: 4, 8, 12, 16...
Multiples of 6: 6, 12, 18...
LCD = 12

Frequently Asked Questions

How do I add fractions with different denominators?

Find the Least Common Denominator (LCD), convert both fractions to equivalent fractions with that denominator, then add numerators. Example: 1/3 + 1/4. LCD = 12. Convert: 4/12 + 3/12 = 7/12.

How do I multiply fractions?

Multiply numerators together and denominators together. Then simplify. Example: 2/3 × 3/5 = (2×3)/(3×5) = 6/15 = 2/5. You can also cross-cancel before multiplying to simplify first.

How do I divide fractions?

Flip (take reciprocal of) the second fraction and multiply. Example: 2/3 ÷ 4/5 = 2/3 × 5/4 = 10/12 = 5/6. The phrase 'flip and multiply' or 'keep, change, flip' is the standard method.

How do I simplify a fraction?

Divide both the numerator and denominator by their Greatest Common Divisor (GCD). For 18/24: GCD(18,24) = 6. Simplified: 18÷6 / 24÷6 = 3/4. A fraction is fully simplified when GCD of numerator and denominator = 1.

How do I convert a mixed number to an improper fraction?

Multiply the whole number by the denominator, add the numerator, keep the same denominator. Example: 3 2/5 = (3×5 + 2)/5 = 17/5. To convert back: divide numerator by denominator, remainder becomes new numerator.

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