What is 18/29 plus 15/21? (Answer: 271/203)

Exact Answer

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Problem: What is 18/29 plus 15/21?
Formula / Expression: 18/29 + 15/21
Final Answer: 1 68/203 (271/203)
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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 18/29 by 21, and multiply the numerator and denominator of 15/21 by 29 so both fractions share the common base 609.
Working: 18 × 21/29 × 21 = 378/609 and 15 × 29/21 × 29 = 435/609

Step 3: Add the Numerators
Now add the numerators (378 + 435 = 813) and keep the common denominator 609 unchanged.
Working: 378 + 435/609 = 813/609

Step 4: Simplify the Fraction to Lowest Terms
Find the Greatest Common Divisor (GCD) of 813 and 609, which is 3. Divide both the numerator and denominator by 3.
Working: 813 ÷ 3/609 ÷ 3 = 271/203

Step 5: Convert Improper Fraction to a Mixed Number
Since the numerator (271) is greater than the denominator (203), divide 271 by 203: it goes in 1 whole time(s) with a remainder of 68, giving the mixed number 1 68/203.
Working: 271/203 = 1 68/203

Step 6: Decimal & Percentage Representation
Dividing the numerator 271 by denominator 203 produces a repeating decimal (approximately 1.334975, or 133.4975%).
Working: 271 ÷ 203 = 1.334975 (133.4975%)

Key Values:
- Simplified Fraction: 271/203
- Mixed Number Form: 1 68/203
- Decimal Value: 1.334975
- Percentage: 133.4975%

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18/29 + 15/21 = 271/203

Simplified Fraction

271/203

Mixed Number

1 68/203

Decimal Value

1.334975

Percentage

133.4975%

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Step-by-Step Solution: 18/29 + 15/21

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 18/29 by 21, and multiply the numerator and denominator of 15/21 by 29 so both fractions share the common base 609.

18 × 21/29 × 21 = 378/609 and 15 × 29/21 × 29 = 435/609

Step 3

Add the Numerators

Now add the numerators (378 + 435 = 813) and keep the common denominator 609 unchanged.

378 + 435/609 = 813/609

Step 4

Simplify the Fraction to Lowest Terms

Find the Greatest Common Divisor (GCD) of 813 and 609, which is 3. Divide both the numerator and denominator by 3.

813 ÷ 3/609 ÷ 3 = 271/203

Step 5

Convert Improper Fraction to a Mixed Number

Since the numerator (271) is greater than the denominator (203), divide 271 by 203: it goes in 1 whole time(s) with a remainder of 68, giving the mixed number 1 68/203.

271/203 = 168/203

Step 6

Decimal & Percentage Representation

Dividing the numerator 271 by denominator 203 produces a repeating decimal (approximately 1.334975, or 133.4975%).

271 ÷ 203 = 1.334975 (133.4975%)

Visual Representation

The diagram below illustrates 18/29 plus 15/21 visually:

Summary & Alternative Representations

Property / Format	Value
Lowest Terms Fraction	`271/203`
Mixed Number Form	`1 68/203`
Decimal Form	`1.334975`
Percentage	`133.4975%`

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Frequently Asked Questions

What is 18/29 plus 15/21 as a fraction?

18/29 + 15/21 in simplest fraction form is 271/203 (or 1 68/203 as a mixed number).

What is 18/29 plus 15/21 as a decimal?

18/29 + 15/21 converted to a decimal is 1.334975.

What is 18/29 plus 15/21 as a percentage?

18/29 + 15/21 expressed as a percentage is 133.4975%.

How do you write 18/29 plus 15/21 as a mixed number?

Because the numerator is greater than the denominator, the improper fraction 271/203 can be written as the mixed number 1 68/203.

Does 18/29 plus 15/21 result in a terminating or repeating decimal?

It results in a repeating decimal (approximately 1.334975...) because the denominator contains prime factors other than 2 and 5.