What is 3/9 plus 9/13? (Answer: 40/39)

Exact Answer

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Problem: What is 3/9 plus 9/13?
Formula / Expression: 3/9 + 9/13
Final Answer: 1 1/39 (40/39)
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Step-by-Step Solution:

Step 1: Find the Least Common Denominator (LCD)
The denominators 9 and 13 are coprime (they share no common factors other than 1). Therefore, their Least Common Denominator (LCD) is simply their direct product: 9 × 13 = 117.
Working: LCD(9, 13) = 117

Step 2: Convert to Equivalent Fractions with Common Denominator 117
Multiply the numerator and denominator of 3/9 by 13, and multiply the numerator and denominator of 9/13 by 9 so both fractions share the common base 117.
Working: 3 × 13/9 × 13 = 39/117 and 9 × 9/13 × 9 = 81/117

Step 3: Add the Numerators
Now add the numerators (39 + 81 = 120) and keep the common denominator 117 unchanged.
Working: 39 + 81/117 = 120/117

Step 4: Simplify the Fraction to Lowest Terms
Find the Greatest Common Divisor (GCD) of 120 and 117, which is 3. Divide both the numerator and denominator by 3.
Working: 120 ÷ 3/117 ÷ 3 = 40/39

Step 5: Convert Improper Fraction to a Mixed Number
Since the numerator (40) is greater than the denominator (39), divide 40 by 39: it goes in 1 whole time(s) with a remainder of 1, giving the mixed number 1 1/39.
Working: 40/39 = 1 1/39

Step 6: Decimal & Percentage Representation
Dividing the numerator 40 by denominator 39 produces a repeating decimal (approximately 1.025641, or 102.5641%).
Working: 40 ÷ 39 = 1.025641 (102.5641%)

Key Values:
- Simplified Fraction: 40/39
- Mixed Number Form: 1 1/39
- Decimal Value: 1.025641
- Percentage: 102.5641%

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Solved with FractionsCalc:
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3/9 + 9/13 = 40/39

Simplified Fraction

40/39

Mixed Number

1 1/39

Decimal Value

1.025641

Percentage

102.5641%

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Step-by-Step Solution: 3/9 + 9/13

Step 1

Find the Least Common Denominator (LCD)

The denominators 9 and 13 are coprime (they share no common factors other than 1). Therefore, their Least Common Denominator (LCD) is simply their direct product: 9 × 13 = 117.

LCD(9, 13) = 117

Step 2

Convert to Equivalent Fractions with Common Denominator 117

Multiply the numerator and denominator of 3/9 by 13, and multiply the numerator and denominator of 9/13 by 9 so both fractions share the common base 117.

3 × 13/9 × 13 = 39/117 and 9 × 9/13 × 9 = 81/117

Step 3

Add the Numerators

Now add the numerators (39 + 81 = 120) and keep the common denominator 117 unchanged.

39 + 81/117 = 120/117

Step 4

Simplify the Fraction to Lowest Terms

Find the Greatest Common Divisor (GCD) of 120 and 117, which is 3. Divide both the numerator and denominator by 3.

120 ÷ 3/117 ÷ 3 = 40/39

Step 5

Convert Improper Fraction to a Mixed Number

Since the numerator (40) is greater than the denominator (39), divide 40 by 39: it goes in 1 whole time(s) with a remainder of 1, giving the mixed number 1 1/39.

40/39 = 11/39

Step 6

Decimal & Percentage Representation

Dividing the numerator 40 by denominator 39 produces a repeating decimal (approximately 1.025641, or 102.5641%).

40 ÷ 39 = 1.025641 (102.5641%)

Visual Representation

The diagram below illustrates 3/9 plus 9/13 visually:

Summary & Alternative Representations

Property / Format	Value
Lowest Terms Fraction	`40/39`
Mixed Number Form	`1 1/39`
Decimal Form	`1.025641`
Percentage	`102.5641%`

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Frequently Asked Questions

What is 3/9 plus 9/13 as a fraction?

3/9 + 9/13 in simplest fraction form is 40/39 (or 1 1/39 as a mixed number).

What is 3/9 plus 9/13 as a decimal?

3/9 + 9/13 converted to a decimal is 1.025641.

What is 3/9 plus 9/13 as a percentage?

3/9 + 9/13 expressed as a percentage is 102.5641%.

How do you write 3/9 plus 9/13 as a mixed number?

Because the numerator is greater than the denominator, the improper fraction 40/39 can be written as the mixed number 1 1/39.

Does 3/9 plus 9/13 result in a terminating or repeating decimal?

It results in a repeating decimal (approximately 1.025641...) because the denominator contains prime factors other than 2 and 5.