What is 1/5 plus 2/7? (Answer: 17/35)

Exact Answer

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Problem: What is 1/5 plus 2/7?
Formula / Expression: 1/5 + 2/7
Final Answer: 17/35
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Step-by-Step Solution:

Step 1: Find the Least Common Denominator (LCD)
The denominators 5 and 7 are coprime (they share no common factors other than 1). Therefore, their Least Common Denominator (LCD) is simply their direct product: 5 × 7 = 35.
Working: LCD(5, 7) = 35

Step 2: Convert to Equivalent Fractions with Common Denominator 35
Multiply the numerator and denominator of 1/5 by 7, and multiply the numerator and denominator of 2/7 by 5 so both fractions share the common base 35.
Working: 1 × 7/5 × 7 = 7/35 and 2 × 5/7 × 5 = 10/35

Step 3: Add the Numerators
Now add the numerators (7 + 10 = 17) and keep the common denominator 35 unchanged.
Working: 7 + 10/35 = 17/35

Step 4: Check if the Fraction Can Be Simplified
The Greatest Common Divisor (GCD) of 17 and 35 is 1, confirming that 17/35 cannot be reduced further—it is already in its simplest irreducible form.
Working: 17/35

Step 5: Decimal & Percentage Representation
Dividing the numerator 17 by denominator 35 produces a repeating decimal (approximately 0.485714, or 48.5714%).
Working: 17 ÷ 35 = 0.485714 (48.5714%)

Key Values:
- Simplified Fraction: 17/35
- Mixed Number Form: 17/35
- Decimal Value: 0.485714
- Percentage: 48.5714%

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Solved with FractionsCalc:
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1/5 + 2/7 = 17/35

Simplified Fraction

17/35

Mixed Number

Proper (17/35)

Decimal Value

0.485714

Percentage

48.5714%

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Step-by-Step Solution: 1/5 + 2/7

Step 1

Find the Least Common Denominator (LCD)

The denominators 5 and 7 are coprime (they share no common factors other than 1). Therefore, their Least Common Denominator (LCD) is simply their direct product: 5 × 7 = 35.

LCD(5, 7) = 35

Step 2

Convert to Equivalent Fractions with Common Denominator 35

Multiply the numerator and denominator of 1/5 by 7, and multiply the numerator and denominator of 2/7 by 5 so both fractions share the common base 35.

1 × 7/5 × 7 = 7/35 and 2 × 5/7 × 5 = 10/35

Step 3

Add the Numerators

Now add the numerators (7 + 10 = 17) and keep the common denominator 35 unchanged.

7 + 10/35 = 17/35

Step 4

Check if the Fraction Can Be Simplified

The Greatest Common Divisor (GCD) of 17 and 35 is 1, confirming that 17/35 cannot be reduced further—it is already in its simplest irreducible form.

17/35

Step 5

Decimal & Percentage Representation

Dividing the numerator 17 by denominator 35 produces a repeating decimal (approximately 0.485714, or 48.5714%).

17 ÷ 35 = 0.485714 (48.5714%)

Visual Representation

The diagram below illustrates 1/5 plus 2/7 visually:

Summary & Alternative Representations

Property / Format	Value
Lowest Terms Fraction	`17/35`
Mixed Number Form	`17/35`
Decimal Form	`0.485714`
Percentage	`48.5714%`

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Frequently Asked Questions

What is 1/5 plus 2/7 as a fraction?

1/5 + 2/7 in simplest fraction form is 17/35.

What is 1/5 plus 2/7 as a decimal?

1/5 + 2/7 converted to a decimal is 0.485714.

What is 1/5 plus 2/7 as a percentage?

1/5 + 2/7 expressed as a percentage is 48.5714%.

Does 1/5 plus 2/7 result in a terminating or repeating decimal?

It results in a repeating decimal (approximately 0.485714...) because the denominator contains prime factors other than 2 and 5.