What is 2/15 plus 4/21? (Answer: 34/105)

Exact Answer

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Problem: What is 2/15 plus 4/21?
Formula / Expression: 2/15 + 4/21
Final Answer: 34/105
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Step-by-Step Solution:

Step 1: Find the Least Common Denominator (LCD)
The denominators 15 and 21 share a common factor (GCD = 3). Finding their Least Common Multiple gives an LCD of 105 (which is smaller than their product 15 × 21 = 315, keeping the calculation simpler).
Working: LCD(15, 21) = 105

Step 2: Convert to Equivalent Fractions with Common Denominator 105
Multiply the numerator and denominator of 2/15 by 7, and multiply the numerator and denominator of 4/21 by 5 so both fractions share the common base 105.
Working: 2 × 7/15 × 7 = 14/105 and 4 × 5/21 × 5 = 20/105

Step 3: Add the Numerators
Now add the numerators (14 + 20 = 34) and keep the common denominator 105 unchanged.
Working: 14 + 20/105 = 34/105

Step 4: Check if the Fraction Can Be Simplified
The Greatest Common Divisor (GCD) of 34 and 105 is 1, confirming that 34/105 cannot be reduced further—it is already in its simplest irreducible form.
Working: 34/105

Step 5: Decimal & Percentage Representation
Dividing the numerator 34 by denominator 105 produces a repeating decimal (approximately 0.32381, or 32.381%).
Working: 34 ÷ 105 = 0.32381 (32.381%)

Key Values:
- Simplified Fraction: 34/105
- Mixed Number Form: 34/105
- Decimal Value: 0.32381
- Percentage: 32.381%

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Solved with FractionsCalc:
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2/15 + 4/21 = 34/105

Simplified Fraction

34/105

Mixed Number

Proper (34/105)

Decimal Value

0.32381

Percentage

32.381%

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Step-by-Step Solution: 2/15 + 4/21

Step 1

Find the Least Common Denominator (LCD)

The denominators 15 and 21 share a common factor (GCD = 3). Finding their Least Common Multiple gives an LCD of 105 (which is smaller than their product 15 × 21 = 315, keeping the calculation simpler).

LCD(15, 21) = 105

Step 2

Convert to Equivalent Fractions with Common Denominator 105

Multiply the numerator and denominator of 2/15 by 7, and multiply the numerator and denominator of 4/21 by 5 so both fractions share the common base 105.

2 × 7/15 × 7 = 14/105 and 4 × 5/21 × 5 = 20/105

Step 3

Add the Numerators

Now add the numerators (14 + 20 = 34) and keep the common denominator 105 unchanged.

14 + 20/105 = 34/105

Step 4

Check if the Fraction Can Be Simplified

The Greatest Common Divisor (GCD) of 34 and 105 is 1, confirming that 34/105 cannot be reduced further—it is already in its simplest irreducible form.

34/105

Step 5

Decimal & Percentage Representation

Dividing the numerator 34 by denominator 105 produces a repeating decimal (approximately 0.32381, or 32.381%).

34 ÷ 105 = 0.32381 (32.381%)

Visual Representation

The diagram below illustrates 2/15 plus 4/21 visually:

Summary & Alternative Representations

Property / Format	Value
Lowest Terms Fraction	`34/105`
Mixed Number Form	`34/105`
Decimal Form	`0.32381`
Percentage	`32.381%`

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Frequently Asked Questions

What is 2/15 plus 4/21 as a fraction?

2/15 + 4/21 in simplest fraction form is 34/105.

What is 2/15 plus 4/21 as a decimal?

2/15 + 4/21 converted to a decimal is 0.32381.

What is 2/15 plus 4/21 as a percentage?

2/15 + 4/21 expressed as a percentage is 32.381%.

Does 2/15 plus 4/21 result in a terminating or repeating decimal?

It results in a repeating decimal (approximately 0.32381...) because the denominator contains prime factors other than 2 and 5.