What is 8/16 plus 12/21? (Answer: 15/14)

Exact Answer

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Problem: What is 8/16 plus 12/21?
Formula / Expression: 8/16 + 12/21
Final Answer: 1 1/14 (15/14)
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Step-by-Step Solution:

Step 1: Find the Least Common Denominator (LCD)
The denominators 16 and 21 are coprime (they share no common factors other than 1). Therefore, their Least Common Denominator (LCD) is simply their direct product: 16 × 21 = 336.
Working: LCD(16, 21) = 336

Step 2: Convert to Equivalent Fractions with Common Denominator 336
Multiply the numerator and denominator of 8/16 by 21, and multiply the numerator and denominator of 12/21 by 16 so both fractions share the common base 336.
Working: 8 × 21/16 × 21 = 168/336 and 12 × 16/21 × 16 = 192/336

Step 3: Add the Numerators
Now add the numerators (168 + 192 = 360) and keep the common denominator 336 unchanged.
Working: 168 + 192/336 = 360/336

Step 4: Simplify the Fraction to Lowest Terms
Find the Greatest Common Divisor (GCD) of 360 and 336, which is 24. Divide both the numerator and denominator by 24.
Working: 360 ÷ 24/336 ÷ 24 = 15/14

Step 5: Convert Improper Fraction to a Mixed Number
Since the numerator (15) is greater than the denominator (14), divide 15 by 14: it goes in 1 whole time(s) with a remainder of 1, giving the mixed number 1 1/14.
Working: 15/14 = 1 1/14

Step 6: Decimal & Percentage Representation
Dividing the numerator 15 by denominator 14 produces a repeating decimal (approximately 1.071429, or 107.1429%).
Working: 15 ÷ 14 = 1.071429 (107.1429%)

Key Values:
- Simplified Fraction: 15/14
- Mixed Number Form: 1 1/14
- Decimal Value: 1.071429
- Percentage: 107.1429%

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Solved with FractionsCalc:
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8/16 + 12/21 = 15/14

Simplified Fraction

15/14

Mixed Number

1 1/14

Decimal Value

1.071429

Percentage

107.1429%

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Step-by-Step Solution: 8/16 + 12/21

Step 1

Find the Least Common Denominator (LCD)

The denominators 16 and 21 are coprime (they share no common factors other than 1). Therefore, their Least Common Denominator (LCD) is simply their direct product: 16 × 21 = 336.

LCD(16, 21) = 336

Step 2

Convert to Equivalent Fractions with Common Denominator 336

Multiply the numerator and denominator of 8/16 by 21, and multiply the numerator and denominator of 12/21 by 16 so both fractions share the common base 336.

8 × 21/16 × 21 = 168/336 and 12 × 16/21 × 16 = 192/336

Step 3

Add the Numerators

Now add the numerators (168 + 192 = 360) and keep the common denominator 336 unchanged.

168 + 192/336 = 360/336

Step 4

Simplify the Fraction to Lowest Terms

Find the Greatest Common Divisor (GCD) of 360 and 336, which is 24. Divide both the numerator and denominator by 24.

360 ÷ 24/336 ÷ 24 = 15/14

Step 5

Convert Improper Fraction to a Mixed Number

Since the numerator (15) is greater than the denominator (14), divide 15 by 14: it goes in 1 whole time(s) with a remainder of 1, giving the mixed number 1 1/14.

15/14 = 11/14

Step 6

Decimal & Percentage Representation

Dividing the numerator 15 by denominator 14 produces a repeating decimal (approximately 1.071429, or 107.1429%).

15 ÷ 14 = 1.071429 (107.1429%)

Visual Representation

The diagram below illustrates 8/16 plus 12/21 visually:

Summary & Alternative Representations

Property / Format	Value
Lowest Terms Fraction	`15/14`
Mixed Number Form	`1 1/14`
Decimal Form	`1.071429`
Percentage	`107.1429%`

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Frequently Asked Questions

What is 8/16 plus 12/21 as a fraction?

8/16 + 12/21 in simplest fraction form is 15/14 (or 1 1/14 as a mixed number).

What is 8/16 plus 12/21 as a decimal?

8/16 + 12/21 converted to a decimal is 1.071429.

What is 8/16 plus 12/21 as a percentage?

8/16 + 12/21 expressed as a percentage is 107.1429%.

How do you write 8/16 plus 12/21 as a mixed number?

Because the numerator is greater than the denominator, the improper fraction 15/14 can be written as the mixed number 1 1/14.

Does 8/16 plus 12/21 result in a terminating or repeating decimal?

It results in a repeating decimal (approximately 1.071429...) because the denominator contains prime factors other than 2 and 5.