What is 8/51 plus 5/21? (Answer: 47/119)

Exact Answer

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Problem: What is 8/51 plus 5/21?
Formula / Expression: 8/51 + 5/21
Final Answer: 47/119
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Step-by-Step Solution:

Step 1: Find the Least Common Denominator (LCD)
The denominators 51 and 21 share a common factor (GCD = 3). Finding their Least Common Multiple gives an LCD of 357 (which is smaller than their product 51 × 21 = 1071, keeping the calculation simpler).
Working: LCD(51, 21) = 357

Step 2: Convert to Equivalent Fractions with Common Denominator 357
Multiply the numerator and denominator of 8/51 by 7, and multiply the numerator and denominator of 5/21 by 17 so both fractions share the common base 357.
Working: 8 × 7/51 × 7 = 56/357 and 5 × 17/21 × 17 = 85/357

Step 3: Add the Numerators
Now add the numerators (56 + 85 = 141) and keep the common denominator 357 unchanged.
Working: 56 + 85/357 = 141/357

Step 4: Simplify the Fraction to Lowest Terms
Find the Greatest Common Divisor (GCD) of 141 and 357, which is 3. Divide both the numerator and denominator by 3.
Working: 141 ÷ 3/357 ÷ 3 = 47/119

Step 5: Decimal & Percentage Representation
Dividing the numerator 47 by denominator 119 produces a repeating decimal (approximately 0.394958, or 39.4958%).
Working: 47 ÷ 119 = 0.394958 (39.4958%)

Key Values:
- Simplified Fraction: 47/119
- Mixed Number Form: 47/119
- Decimal Value: 0.394958
- Percentage: 39.4958%

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Solved with FractionsCalc:
https://fractionscalc.com/what-is-8-51-plus-5-21/
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8/51 + 5/21 = 47/119

Simplified Fraction

47/119

Mixed Number

Proper (47/119)

Decimal Value

0.394958

Percentage

39.4958%

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Step-by-Step Solution: 8/51 + 5/21

Step 1

Find the Least Common Denominator (LCD)

The denominators 51 and 21 share a common factor (GCD = 3). Finding their Least Common Multiple gives an LCD of 357 (which is smaller than their product 51 × 21 = 1071, keeping the calculation simpler).

LCD(51, 21) = 357

Step 2

Convert to Equivalent Fractions with Common Denominator 357

Multiply the numerator and denominator of 8/51 by 7, and multiply the numerator and denominator of 5/21 by 17 so both fractions share the common base 357.

8 × 7/51 × 7 = 56/357 and 5 × 17/21 × 17 = 85/357

Step 3

Add the Numerators

Now add the numerators (56 + 85 = 141) and keep the common denominator 357 unchanged.

56 + 85/357 = 141/357

Step 4

Simplify the Fraction to Lowest Terms

Find the Greatest Common Divisor (GCD) of 141 and 357, which is 3. Divide both the numerator and denominator by 3.

141 ÷ 3/357 ÷ 3 = 47/119

Step 5

Decimal & Percentage Representation

Dividing the numerator 47 by denominator 119 produces a repeating decimal (approximately 0.394958, or 39.4958%).

47 ÷ 119 = 0.394958 (39.4958%)

Visual Representation

The diagram below illustrates 8/51 plus 5/21 visually:

Summary & Alternative Representations

Property / Format	Value
Lowest Terms Fraction	`47/119`
Mixed Number Form	`47/119`
Decimal Form	`0.394958`
Percentage	`39.4958%`

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Frequently Asked Questions

What is 8/51 plus 5/21 as a fraction?

8/51 + 5/21 in simplest fraction form is 47/119.

What is 8/51 plus 5/21 as a decimal?

8/51 + 5/21 converted to a decimal is 0.394958.

What is 8/51 plus 5/21 as a percentage?

8/51 + 5/21 expressed as a percentage is 39.4958%.

Does 8/51 plus 5/21 result in a terminating or repeating decimal?

It results in a repeating decimal (approximately 0.394958...) because the denominator contains prime factors other than 2 and 5.