Solve Fraction Addition: 5/12 + 11/36 Step by Step

Fraction Addition with Different Denominators

512+1136= \frac{5}{12}+\frac{11}{36}=

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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 Therefore multiply by 3, to get the common denominator 36
00:09 Remember to multiply both numerator and denominator
00:18 Calculate the multiplications
00:26 Add under the common denominator
00:36 Calculate the numerator
00:43 Reduce the fraction as much as possible
00:48 Remember to divide both numerator and denominator
00:53 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

512+1136= \frac{5}{12}+\frac{11}{36}=

2

Step-by-step solution

To solve this problem, we'll follow these steps:

  • Step 1: Identify the least common denominator (LCD) of the fractions.
  • Step 2: Rewrite the fractions with the common denominator.
  • Step 3: Add the fractions.
  • Step 4: Simplify the resulting fraction.

Let's work through these steps:

Step 1: The denominators of our fractions are 12 and 36. The least common denominator is 36. This is because 36 is the smallest number that both 12 and 36 divide into evenly.

Step 2: Rewrite 512 \frac{5}{12} with the denominator 36. To do this, find what number 12 must be multiplied by to become 36, which is 3. Thus, multiply both the numerator and the denominator of 512 \frac{5}{12} by 3:

512=5×312×3=1536 \frac{5}{12} = \frac{5 \times 3}{12 \times 3} = \frac{15}{36} .

Step 3: Now add the fractions 1536 \frac{15}{36} and 1136 \frac{11}{36} , since they have a common denominator:

1536+1136=15+1136=2636 \frac{15}{36} + \frac{11}{36} = \frac{15 + 11}{36} = \frac{26}{36} .

Step 4: Simplify 2636 \frac{26}{36} . The greatest common divisor (GCD) of 26 and 36 is 2. Divide both the numerator and the denominator by 2:

2636=26÷236÷2=1318 \frac{26}{36} = \frac{26 \div 2}{36 \div 2} = \frac{13}{18} .

Therefore, the sum of 512+1136 \frac{5}{12} + \frac{11}{36} is 1318 \frac{13}{18} .

The correct choice that matches this solution is choice 4.

3

Final Answer

1318 \frac{13}{18}

Key Points to Remember

Essential concepts to master this topic
  • LCD Rule: Find least common denominator before adding fractions
  • Technique: Convert 512 \frac{5}{12} to 1536 \frac{15}{36} by multiplying by 3
  • Check: Simplify final answer by dividing by GCD: 2636=1318 \frac{26}{36} = \frac{13}{18}

Common Mistakes

Avoid these frequent errors
  • Adding numerators and denominators separately
    Don't add 512+1136=1648 \frac{5}{12} + \frac{11}{36} = \frac{16}{48} ! This ignores that fractions need common denominators first. Always find the LCD, convert both fractions, then add only the numerators.

Practice Quiz

Test your knowledge with interactive questions

\( \)\( \frac{4}{5}+\frac{1}{5}= \)

FAQ

Everything you need to know about this question

How do I find the least common denominator of 12 and 36?

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Since 36 is already a multiple of 12 (12 × 3 = 36), the LCD is simply 36! When one denominator divides evenly into the other, the larger number is always the LCD.

Why can't I just add the fractions as they are?

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Fractions must have the same denominator to add them. Think of it like adding different sized pieces - you need to make them the same size first!

What if I forget to simplify my answer?

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Your answer would be mathematically correct but not in simplest form. Teachers usually want simplified answers, so always check if you can divide both numerator and denominator by their GCD.

How do I know if 13/18 can be simplified further?

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Find the GCD of 13 and 18. Since 13 is prime and doesn't divide 18, the GCD is 1. This means 1318 \frac{13}{18} is already in simplest form!

What if the denominators don't have an obvious relationship?

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Use the prime factorization method or multiply the denominators together, then divide by their GCD. For example, LCD of 8 and 12 would be 24.

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