4th Grade Math

Fractions, decimals, and geometric concepts for fourth grade students.

Advanced Topics

Adding and Subtracting Fractions

How to Add and Subtract Fractions

To add or subtract fractions, they must have the same denominator (the bottom number). If they don't, you need to find a common denominator.

  • If denominators are the same, just add or subtract the numerators:

    • \( \frac{2}{8} + \frac{3}{8} = \frac{5}{8} \)
  • If denominators are different, make them the same first.

Real-Life Uses

Adding fractions is helpful when following recipes or combining lengths.

Tips for Success

Always check if you need to simplify your answer!

Key Formula

\[\frac{a}{b} + \frac{c}{b} = \frac{a+c}{b}\]

Examples

  • Combining \( \frac{1}{4} \) cup of sugar and \( \frac{1}{4} \) cup of flour gives \( \frac{2}{4} \) cups.

  • Subtracting \( \frac{2}{5} \) of a ribbon from \( \frac{4}{5} \) leaves \( \frac{2}{5} \) of the ribbon.

In a Nutshell

Add or subtract fractions by making the denominators the same.

Key Terms

Common Denominator
A shared denominator between two or more fractions.
Simplify
To reduce a fraction to its smallest possible numerator and denominator.