What is 12/29 plus 9/21? (Answer: 171/203)

Exact Answer

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Problem: What is 12/29 plus 9/21?
Formula / Expression: 12/29 + 9/21
Final Answer: 171/203
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Step-by-Step Solution:

Step 1: Find the Least Common Denominator (LCD)
The denominators 29 and 21 are coprime (they share no common factors other than 1). Therefore, their Least Common Denominator (LCD) is simply their direct product: 29 × 21 = 609.
Working: LCD(29, 21) = 609

Step 2: Convert to Equivalent Fractions with Common Denominator 609
Multiply the numerator and denominator of 12/29 by 21, and multiply the numerator and denominator of 9/21 by 29 so both fractions share the common base 609.
Working: 12 × 21/29 × 21 = 252/609 and 9 × 29/21 × 29 = 261/609

Step 3: Add the Numerators
Now add the numerators (252 + 261 = 513) and keep the common denominator 609 unchanged.
Working: 252 + 261/609 = 513/609

Step 4: Simplify the Fraction to Lowest Terms
Find the Greatest Common Divisor (GCD) of 513 and 609, which is 3. Divide both the numerator and denominator by 3.
Working: 513 ÷ 3/609 ÷ 3 = 171/203

Step 5: Decimal & Percentage Representation
Dividing the numerator 171 by denominator 203 produces a repeating decimal (approximately 0.842365, or 84.2365%).
Working: 171 ÷ 203 = 0.842365 (84.2365%)

Key Values:
- Simplified Fraction: 171/203
- Mixed Number Form: 171/203
- Decimal Value: 0.842365
- Percentage: 84.2365%

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Solved with FractionsCalc:
https://fractionscalc.com/what-is-12-29-plus-9-21/
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12/29 + 9/21 = 171/203

Simplified Fraction

171/203

Mixed Number

Proper (171/203)

Decimal Value

0.842365

Percentage

84.2365%

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Step-by-Step Solution: 12/29 + 9/21

Step 1

Find the Least Common Denominator (LCD)

The denominators 29 and 21 are coprime (they share no common factors other than 1). Therefore, their Least Common Denominator (LCD) is simply their direct product: 29 × 21 = 609.

LCD(29, 21) = 609

Step 2

Convert to Equivalent Fractions with Common Denominator 609

Multiply the numerator and denominator of 12/29 by 21, and multiply the numerator and denominator of 9/21 by 29 so both fractions share the common base 609.

12 × 21/29 × 21 = 252/609 and 9 × 29/21 × 29 = 261/609

Step 3

Add the Numerators

Now add the numerators (252 + 261 = 513) and keep the common denominator 609 unchanged.

252 + 261/609 = 513/609

Step 4

Simplify the Fraction to Lowest Terms

Find the Greatest Common Divisor (GCD) of 513 and 609, which is 3. Divide both the numerator and denominator by 3.

513 ÷ 3/609 ÷ 3 = 171/203

Step 5

Decimal & Percentage Representation

Dividing the numerator 171 by denominator 203 produces a repeating decimal (approximately 0.842365, or 84.2365%).

171 ÷ 203 = 0.842365 (84.2365%)

Visual Representation

The diagram below illustrates 12/29 plus 9/21 visually:

Summary & Alternative Representations

Property / Format	Value
Lowest Terms Fraction	`171/203`
Mixed Number Form	`171/203`
Decimal Form	`0.842365`
Percentage	`84.2365%`

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Frequently Asked Questions

What is 12/29 plus 9/21 as a fraction?

12/29 + 9/21 in simplest fraction form is 171/203.

What is 12/29 plus 9/21 as a decimal?

12/29 + 9/21 converted to a decimal is 0.842365.

What is 12/29 plus 9/21 as a percentage?

12/29 + 9/21 expressed as a percentage is 84.2365%.

Does 12/29 plus 9/21 result in a terminating or repeating decimal?

It results in a repeating decimal (approximately 0.842365...) because the denominator contains prime factors other than 2 and 5.