What is 9/13 plus 12/17? (Answer: 309/221)

Exact Answer

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Problem: What is 9/13 plus 12/17?
Formula / Expression: 9/13 + 12/17
Final Answer: 1 88/221 (309/221)
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Step-by-Step Solution:

Step 1: Find the Least Common Denominator (LCD)
The denominators 13 and 17 are coprime (they share no common factors other than 1). Therefore, their Least Common Denominator (LCD) is simply their direct product: 13 × 17 = 221.
Working: LCD(13, 17) = 221

Step 2: Convert to Equivalent Fractions with Common Denominator 221
Multiply the numerator and denominator of 9/13 by 17, and multiply the numerator and denominator of 12/17 by 13 so both fractions share the common base 221.
Working: 9 × 17/13 × 17 = 153/221 and 12 × 13/17 × 13 = 156/221

Step 3: Add the Numerators
Now add the numerators (153 + 156 = 309) and keep the common denominator 221 unchanged.
Working: 153 + 156/221 = 309/221

Step 4: Check if the Fraction Can Be Simplified
The Greatest Common Divisor (GCD) of 309 and 221 is 1, confirming that 309/221 cannot be reduced further—it is already in its simplest irreducible form.
Working: 309/221

Step 5: Convert Improper Fraction to a Mixed Number
Since the numerator (309) is greater than the denominator (221), divide 309 by 221: it goes in 1 whole time(s) with a remainder of 88, giving the mixed number 1 88/221.
Working: 309/221 = 1 88/221

Step 6: Decimal & Percentage Representation
Dividing the numerator 309 by denominator 221 produces a repeating decimal (approximately 1.39819, or 139.819%).
Working: 309 ÷ 221 = 1.39819 (139.819%)

Key Values:
- Simplified Fraction: 309/221
- Mixed Number Form: 1 88/221
- Decimal Value: 1.39819
- Percentage: 139.819%

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Solved with FractionsCalc:
https://fractionscalc.com/what-is-9-13-plus-12-17/
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9/13 + 12/17 = 309/221

Simplified Fraction

309/221

Mixed Number

1 88/221

Decimal Value

1.39819

Percentage

139.819%

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Step-by-Step Solution: 9/13 + 12/17

Step 1

Find the Least Common Denominator (LCD)

The denominators 13 and 17 are coprime (they share no common factors other than 1). Therefore, their Least Common Denominator (LCD) is simply their direct product: 13 × 17 = 221.

LCD(13, 17) = 221

Step 2

Convert to Equivalent Fractions with Common Denominator 221

Multiply the numerator and denominator of 9/13 by 17, and multiply the numerator and denominator of 12/17 by 13 so both fractions share the common base 221.

9 × 17/13 × 17 = 153/221 and 12 × 13/17 × 13 = 156/221

Step 3

Add the Numerators

Now add the numerators (153 + 156 = 309) and keep the common denominator 221 unchanged.

153 + 156/221 = 309/221

Step 4

Check if the Fraction Can Be Simplified

The Greatest Common Divisor (GCD) of 309 and 221 is 1, confirming that 309/221 cannot be reduced further—it is already in its simplest irreducible form.

309/221

Step 5

Convert Improper Fraction to a Mixed Number

Since the numerator (309) is greater than the denominator (221), divide 309 by 221: it goes in 1 whole time(s) with a remainder of 88, giving the mixed number 1 88/221.

309/221 = 188/221

Step 6

Decimal & Percentage Representation

Dividing the numerator 309 by denominator 221 produces a repeating decimal (approximately 1.39819, or 139.819%).

309 ÷ 221 = 1.39819 (139.819%)

Visual Representation

The diagram below illustrates 9/13 plus 12/17 visually:

Summary & Alternative Representations

Property / Format	Value
Lowest Terms Fraction	`309/221`
Mixed Number Form	`1 88/221`
Decimal Form	`1.39819`
Percentage	`139.819%`

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Frequently Asked Questions

What is 9/13 plus 12/17 as a fraction?

9/13 + 12/17 in simplest fraction form is 309/221 (or 1 88/221 as a mixed number).

What is 9/13 plus 12/17 as a decimal?

9/13 + 12/17 converted to a decimal is 1.39819.

What is 9/13 plus 12/17 as a percentage?

9/13 + 12/17 expressed as a percentage is 139.819%.

How do you write 9/13 plus 12/17 as a mixed number?

Because the numerator is greater than the denominator, the improper fraction 309/221 can be written as the mixed number 1 88/221.

Does 9/13 plus 12/17 result in a terminating or repeating decimal?

It results in a repeating decimal (approximately 1.39819...) because the denominator contains prime factors other than 2 and 5.