Explain how to find the least common multiple (LCM) of two numbers.

Start with the larger number and check its multiples until you find one that is divisible by the smaller number.

If you multiply the denominator of a fraction by a certain number to obtain a common denominator, what must you also do to the numerator?

Multiply the numerator by the same number.

Grade 10th Grade · Math · 45 min

I can add and subtract fractions with unlike denominators, including simplifying the resulting fraction.

Khan Academy · 7:23

Adding fractions with unlike denominators

3 key concepts

1
To add fractions with unlike denominators, you must first find a common denominator by determining the least common multiple of the original denominators.
2
Once a common denominator is found, rewrite each fraction with the new denominator by multiplying both the numerator and denominator by the same factor.
3
After adding the fractions, simplify the result if possible by finding a common factor of the numerator and denominator and dividing both by it.

9 questions · Multiple choice & Short answer

Quick comprehension check

“Solve: ⅚ - ⅜. Show all steps, including finding a common denominator and simplifying your answer.”

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