Solve the Fraction Addition: 3/8 + 1/9 Step-by-Step

Fraction Addition with Different Denominators

38+19= \frac{3}{8}+\frac{1}{9}=

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Step-by-step video solution

Watch the teacher solve the problem with clear explanations
00:00 Solve
00:03 We want to find the least common denominator
00:06 Multiply each fraction by the other denominator to find the common denominator
00:09 Remember to multiply both numerator and denominator
00:27 Calculate the multiplications
00:37 Add under the common denominator
00:42 Calculate the numerator
00:49 And this is the solution to the question

Step-by-step written solution

Follow each step carefully to understand the complete solution
1

Understand the problem

38+19= \frac{3}{8}+\frac{1}{9}=

2

Step-by-step solution

To solve the problem of adding the two fractions 38\frac{3}{8} and 19\frac{1}{9}, follow these steps:

  • Step 1: Find the least common denominator (LCD) of the fractions. We calculate 8×9=728 \times 9 = 72. Thus, the LCD is 72.
  • Step 2: Convert each fraction to an equivalent fraction with the LCD as the new denominator.
    • For 38\frac{3}{8}, multiply the numerator and denominator by 9: 3×98×9=2772\frac{3 \times 9}{8 \times 9} = \frac{27}{72}.
    • For 19\frac{1}{9}, multiply the numerator and denominator by 8: 1×89×8=872\frac{1 \times 8}{9 \times 8} = \frac{8}{72}.
  • Step 3: Add the two fractions: 2772+872=27+872=3572\frac{27}{72} + \frac{8}{72} = \frac{27 + 8}{72} = \frac{35}{72}.
  • Step 4: Simplify the resulting fraction if possible. Here, 3572\frac{35}{72} is already in its simplest form.

Thus, the sum of 38\frac{3}{8} and 19\frac{1}{9} is 3572\frac{35}{72}.

Therefore, the solution to the problem is 3572\frac{35}{72}.

3

Final Answer

3572 \frac{35}{72}

Key Points to Remember

Essential concepts to master this topic
  • Common Denominator: Find LCD by multiplying denominators when they share no factors
  • Technique: Convert 38 \frac{3}{8} to 2772 \frac{27}{72} by multiplying by 99 \frac{9}{9}
  • Check: Verify 2772+872=3572 \frac{27}{72} + \frac{8}{72} = \frac{35}{72} cannot simplify further ✓

Common Mistakes

Avoid these frequent errors
  • Adding numerators and denominators separately
    Don't add 38+19 \frac{3}{8} + \frac{1}{9} as 417 \frac{4}{17} ! This completely ignores the need for equal denominators and gives a meaningless result. Always find a common denominator first, then add only the numerators.

Practice Quiz

Test your knowledge with interactive questions

Complete the following exercise:

\( \frac{3}{4}:\frac{5}{6}=\text{?} \)

FAQ

Everything you need to know about this question

Why can't I just add 3+1=4 and 8+9=17?

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Because fractions represent parts of different wholes! 38 \frac{3}{8} means 3 pieces of size 18 \frac{1}{8} , while 19 \frac{1}{9} means 1 piece of size 19 \frac{1}{9} . You need same-sized pieces to add them!

How do I find the LCD when denominators don't divide evenly?

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When denominators like 8 and 9 share no common factors, multiply them together: 8 × 9 = 72. For more complex cases, find the least common multiple using prime factorization.

Do I always need to check if my answer can be simplified?

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Yes! Always check if the numerator and denominator share any common factors. In this case, 35 and 72 share no factors, so 3572 \frac{35}{72} is already fully simplified.

What if I get a really big denominator?

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That's normal! When adding fractions with different denominators, the LCD can be quite large. Focus on accuracy first, then simplify. The math is still the same!

Can I use a different common denominator instead of the LCD?

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You can use any common multiple, but using the LCD keeps numbers smaller and makes calculations easier. Why make extra work for yourself?

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