Least common denominator - Examples, Exercises and Solutions

A common denominator is a denominator that will be common and equal for all the fractions in the exercise. We will reach such a denominator by reducing or enlarging the fraction - an operation of multiplication or division.
We can arrive at several correct common denominators.

We will divide the search for the common denominator into 3 cases:

  • The first case: one of the denominators appearing in the original exercise will be the common denominator.
    In this case, we will notice that we only have to multiply one denominator by an integer to reach the same denominator as in the other fraction.
  • The second case: find a number that both denominators in the exercise can reach by multiplication.
  • The third case: find the common denominator by multiplying the denominators.

Suggested Topics to Practice in Advance

  1. A fraction as a divisor
  2. Numerator
  3. Denominator
  4. Fractions
  5. Part of a quantity
  6. Placing Fractions on the Number Line

Practice Least common denominator

Exercise #1

35+215= \frac{3}{5}+\frac{2}{15}=

Video Solution

Answer

1115 \frac{11}{15}

Exercise #2

15+215= \frac{1}{5}+\frac{2}{15}=

Video Solution

Answer

515 \frac{5}{15}

Exercise #3

24+12= \frac{2}{4}+\frac{1}{2}=

Video Solution

Answer

1 1

Exercise #4

23+16= \frac{2}{3}+\frac{1}{6}=

Video Solution

Answer

56 \frac{5}{6}

Exercise #5

13+36= \frac{1}{3}+\frac{3}{6}=

Video Solution

Answer

56 \frac{5}{6}

Exercise #1

34+18= \frac{3}{4}+\frac{1}{8}=

Video Solution

Answer

78 \frac{7}{8}

Exercise #2

14+68= \frac{1}{4}+\frac{6}{8}=

Video Solution

Answer

1 1

Exercise #3

14+48= \frac{1}{4}+\frac{4}{8}=

Video Solution

Answer

68 \frac{6}{8}

Exercise #4

15+610= \frac{1}{5}+\frac{6}{10}=

Video Solution

Answer

810 \frac{8}{10}

Exercise #5

24+18= \frac{2}{4}+\frac{1}{8}=

Video Solution

Answer

58 \frac{5}{8}

Exercise #1

12+38= \frac{1}{2}+\frac{3}{8}=

Video Solution

Answer

78 \frac{7}{8}

Exercise #2

14+58= \frac{1}{4}+\frac{5}{8}=

Video Solution

Answer

78 \frac{7}{8}

Exercise #3

13+29= \frac{1}{3}+\frac{2}{9}=

Video Solution

Answer

59 \frac{5}{9}

Exercise #4

13+59= \frac{1}{3}+\frac{5}{9}=

Video Solution

Answer

89 \frac{8}{9}

Exercise #5

13+49= \frac{1}{3}+\frac{4}{9}=

Video Solution

Answer

79 \frac{7}{9}

Topics learned in later sections

  1. How do you simplify fractions?
  2. Simplification and Expansion of Simple Fractions