What is 12/28 plus 9/13? (Answer: 102/91)

Exact Answer

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Problem: What is 12/28 plus 9/13?
Formula / Expression: 12/28 + 9/13
Final Answer: 1 11/91 (102/91)
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Step-by-Step Solution:

Step 1: Find the Least Common Denominator (LCD)
The denominators 28 and 13 are coprime (they share no common factors other than 1). Therefore, their Least Common Denominator (LCD) is simply their direct product: 28 × 13 = 364.
Working: LCD(28, 13) = 364

Step 2: Convert to Equivalent Fractions with Common Denominator 364
Multiply the numerator and denominator of 12/28 by 13, and multiply the numerator and denominator of 9/13 by 28 so both fractions share the common base 364.
Working: 12 × 13/28 × 13 = 156/364 and 9 × 28/13 × 28 = 252/364

Step 3: Add the Numerators
Now add the numerators (156 + 252 = 408) and keep the common denominator 364 unchanged.
Working: 156 + 252/364 = 408/364

Step 4: Simplify the Fraction to Lowest Terms
Find the Greatest Common Divisor (GCD) of 408 and 364, which is 4. Divide both the numerator and denominator by 4.
Working: 408 ÷ 4/364 ÷ 4 = 102/91

Step 5: Convert Improper Fraction to a Mixed Number
Since the numerator (102) is greater than the denominator (91), divide 102 by 91: it goes in 1 whole time(s) with a remainder of 11, giving the mixed number 1 11/91.
Working: 102/91 = 1 11/91

Step 6: Decimal & Percentage Representation
Dividing the numerator 102 by denominator 91 produces a repeating decimal (approximately 1.120879, or 112.0879%).
Working: 102 ÷ 91 = 1.120879 (112.0879%)

Key Values:
- Simplified Fraction: 102/91
- Mixed Number Form: 1 11/91
- Decimal Value: 1.120879
- Percentage: 112.0879%

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Solved with FractionsCalc:
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12/28 + 9/13 = 102/91

Simplified Fraction

102/91

Mixed Number

1 11/91

Decimal Value

1.120879

Percentage

112.0879%

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Step-by-Step Solution: 12/28 + 9/13

Step 1

Find the Least Common Denominator (LCD)

The denominators 28 and 13 are coprime (they share no common factors other than 1). Therefore, their Least Common Denominator (LCD) is simply their direct product: 28 × 13 = 364.

LCD(28, 13) = 364

Step 2

Convert to Equivalent Fractions with Common Denominator 364

Multiply the numerator and denominator of 12/28 by 13, and multiply the numerator and denominator of 9/13 by 28 so both fractions share the common base 364.

12 × 13/28 × 13 = 156/364 and 9 × 28/13 × 28 = 252/364

Step 3

Add the Numerators

Now add the numerators (156 + 252 = 408) and keep the common denominator 364 unchanged.

156 + 252/364 = 408/364

Step 4

Simplify the Fraction to Lowest Terms

Find the Greatest Common Divisor (GCD) of 408 and 364, which is 4. Divide both the numerator and denominator by 4.

408 ÷ 4/364 ÷ 4 = 102/91

Step 5

Convert Improper Fraction to a Mixed Number

Since the numerator (102) is greater than the denominator (91), divide 102 by 91: it goes in 1 whole time(s) with a remainder of 11, giving the mixed number 1 11/91.

102/91 = 111/91

Step 6

Decimal & Percentage Representation

Dividing the numerator 102 by denominator 91 produces a repeating decimal (approximately 1.120879, or 112.0879%).

102 ÷ 91 = 1.120879 (112.0879%)

Visual Representation

The diagram below illustrates 12/28 plus 9/13 visually:

Summary & Alternative Representations

Property / Format	Value
Lowest Terms Fraction	`102/91`
Mixed Number Form	`1 11/91`
Decimal Form	`1.120879`
Percentage	`112.0879%`

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Frequently Asked Questions

What is 12/28 plus 9/13 as a fraction?

12/28 + 9/13 in simplest fraction form is 102/91 (or 1 11/91 as a mixed number).

What is 12/28 plus 9/13 as a decimal?

12/28 + 9/13 converted to a decimal is 1.120879.

What is 12/28 plus 9/13 as a percentage?

12/28 + 9/13 expressed as a percentage is 112.0879%.

How do you write 12/28 plus 9/13 as a mixed number?

Because the numerator is greater than the denominator, the improper fraction 102/91 can be written as the mixed number 1 11/91.

Does 12/28 plus 9/13 result in a terminating or repeating decimal?

It results in a repeating decimal (approximately 1.120879...) because the denominator contains prime factors other than 2 and 5.