What is 4/15 plus 6/21? (Answer: 58/105)

Exact Answer

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Problem: What is 4/15 plus 6/21?
Formula / Expression: 4/15 + 6/21
Final Answer: 58/105
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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 4/15 by 7, and multiply the numerator and denominator of 6/21 by 5 so both fractions share the common base 105.
Working: 4 × 7/15 × 7 = 28/105 and 6 × 5/21 × 5 = 30/105

Step 3: Add the Numerators
Now add the numerators (28 + 30 = 58) and keep the common denominator 105 unchanged.
Working: 28 + 30/105 = 58/105

Step 4: Check if the Fraction Can Be Simplified
The Greatest Common Divisor (GCD) of 58 and 105 is 1, confirming that 58/105 cannot be reduced further—it is already in its simplest irreducible form.
Working: 58/105

Step 5: Decimal & Percentage Representation
Dividing the numerator 58 by denominator 105 produces a repeating decimal (approximately 0.552381, or 55.2381%).
Working: 58 ÷ 105 = 0.552381 (55.2381%)

Key Values:
- Simplified Fraction: 58/105
- Mixed Number Form: 58/105
- Decimal Value: 0.552381
- Percentage: 55.2381%

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Solved with FractionsCalc:
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4/15 + 6/21 = 58/105

Simplified Fraction

58/105

Mixed Number

Proper (58/105)

Decimal Value

0.552381

Percentage

55.2381%

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Step-by-Step Solution: 4/15 + 6/21

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 4/15 by 7, and multiply the numerator and denominator of 6/21 by 5 so both fractions share the common base 105.

4 × 7/15 × 7 = 28/105 and 6 × 5/21 × 5 = 30/105

Step 3

Add the Numerators

Now add the numerators (28 + 30 = 58) and keep the common denominator 105 unchanged.

28 + 30/105 = 58/105

Step 4

Check if the Fraction Can Be Simplified

The Greatest Common Divisor (GCD) of 58 and 105 is 1, confirming that 58/105 cannot be reduced further—it is already in its simplest irreducible form.

58/105

Step 5

Decimal & Percentage Representation

Dividing the numerator 58 by denominator 105 produces a repeating decimal (approximately 0.552381, or 55.2381%).

58 ÷ 105 = 0.552381 (55.2381%)

Visual Representation

The diagram below illustrates 4/15 plus 6/21 visually:

Summary & Alternative Representations

Property / Format	Value
Lowest Terms Fraction	`58/105`
Mixed Number Form	`58/105`
Decimal Form	`0.552381`
Percentage	`55.2381%`

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Frequently Asked Questions

What is 4/15 plus 6/21 as a fraction?

4/15 + 6/21 in simplest fraction form is 58/105.

What is 4/15 plus 6/21 as a decimal?

4/15 + 6/21 converted to a decimal is 0.552381.

What is 4/15 plus 6/21 as a percentage?

4/15 + 6/21 expressed as a percentage is 55.2381%.

Does 4/15 plus 6/21 result in a terminating or repeating decimal?

It results in a repeating decimal (approximately 0.552381...) because the denominator contains prime factors other than 2 and 5.