What is 1/15 plus 10/21? (Answer: 19/35)

Exact Answer

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Problem: What is 1/15 plus 10/21?
Formula / Expression: 1/15 + 10/21
Final Answer: 19/35
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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 1/15 by 7, and multiply the numerator and denominator of 10/21 by 5 so both fractions share the common base 105.
Working: 1 × 7/15 × 7 = 7/105 and 10 × 5/21 × 5 = 50/105

Step 3: Add the Numerators
Now add the numerators (7 + 50 = 57) and keep the common denominator 105 unchanged.
Working: 7 + 50/105 = 57/105

Step 4: Simplify the Fraction to Lowest Terms
Find the Greatest Common Divisor (GCD) of 57 and 105, which is 3. Divide both the numerator and denominator by 3.
Working: 57 ÷ 3/105 ÷ 3 = 19/35

Step 5: Decimal & Percentage Representation
Dividing the numerator 19 by denominator 35 produces a repeating decimal (approximately 0.542857, or 54.2857%).
Working: 19 ÷ 35 = 0.542857 (54.2857%)

Key Values:
- Simplified Fraction: 19/35
- Mixed Number Form: 19/35
- Decimal Value: 0.542857
- Percentage: 54.2857%

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Solved with FractionsCalc:
https://fractionscalc.com/what-is-1-15-plus-10-21/
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1/15 + 10/21 = 19/35

Simplified Fraction

19/35

Mixed Number

Proper (19/35)

Decimal Value

0.542857

Percentage

54.2857%

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Step-by-Step Solution: 1/15 + 10/21

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 1/15 by 7, and multiply the numerator and denominator of 10/21 by 5 so both fractions share the common base 105.

1 × 7/15 × 7 = 7/105 and 10 × 5/21 × 5 = 50/105

Step 3

Add the Numerators

Now add the numerators (7 + 50 = 57) and keep the common denominator 105 unchanged.

7 + 50/105 = 57/105

Step 4

Simplify the Fraction to Lowest Terms

Find the Greatest Common Divisor (GCD) of 57 and 105, which is 3. Divide both the numerator and denominator by 3.

57 ÷ 3/105 ÷ 3 = 19/35

Step 5

Decimal & Percentage Representation

Dividing the numerator 19 by denominator 35 produces a repeating decimal (approximately 0.542857, or 54.2857%).

19 ÷ 35 = 0.542857 (54.2857%)

Visual Representation

The diagram below illustrates 1/15 plus 10/21 visually:

Summary & Alternative Representations

Property / Format	Value
Lowest Terms Fraction	`19/35`
Mixed Number Form	`19/35`
Decimal Form	`0.542857`
Percentage	`54.2857%`

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Frequently Asked Questions

What is 1/15 plus 10/21 as a fraction?

1/15 + 10/21 in simplest fraction form is 19/35.

What is 1/15 plus 10/21 as a decimal?

1/15 + 10/21 converted to a decimal is 0.542857.

What is 1/15 plus 10/21 as a percentage?

1/15 + 10/21 expressed as a percentage is 54.2857%.

Does 1/15 plus 10/21 result in a terminating or repeating decimal?

It results in a repeating decimal (approximately 0.542857...) because the denominator contains prime factors other than 2 and 5.