What is 5/20 plus 11/21? (Answer: 65/84)

Exact Answer

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Problem: What is 5/20 plus 11/21?
Formula / Expression: 5/20 + 11/21
Final Answer: 65/84
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Step-by-Step Solution:

Step 1: Find the Least Common Denominator (LCD)
The denominators 20 and 21 are coprime (they share no common factors other than 1). Therefore, their Least Common Denominator (LCD) is simply their direct product: 20 × 21 = 420.
Working: LCD(20, 21) = 420

Step 2: Convert to Equivalent Fractions with Common Denominator 420
Multiply the numerator and denominator of 5/20 by 21, and multiply the numerator and denominator of 11/21 by 20 so both fractions share the common base 420.
Working: 5 × 21/20 × 21 = 105/420 and 11 × 20/21 × 20 = 220/420

Step 3: Add the Numerators
Now add the numerators (105 + 220 = 325) and keep the common denominator 420 unchanged.
Working: 105 + 220/420 = 325/420

Step 4: Simplify the Fraction to Lowest Terms
Find the Greatest Common Divisor (GCD) of 325 and 420, which is 5. Divide both the numerator and denominator by 5.
Working: 325 ÷ 5/420 ÷ 5 = 65/84

Step 5: Decimal & Percentage Representation
Dividing the numerator 65 by denominator 84 produces a repeating decimal (approximately 0.77381, or 77.381%).
Working: 65 ÷ 84 = 0.77381 (77.381%)

Key Values:
- Simplified Fraction: 65/84
- Mixed Number Form: 65/84
- Decimal Value: 0.77381
- Percentage: 77.381%

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Solved with FractionsCalc:
https://fractionscalc.com/what-is-5-20-plus-11-21/
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5/20 + 11/21 = 65/84

Simplified Fraction

65/84

Mixed Number

Proper (65/84)

Decimal Value

0.77381

Percentage

77.381%

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Step-by-Step Solution: 5/20 + 11/21

Step 1

Find the Least Common Denominator (LCD)

The denominators 20 and 21 are coprime (they share no common factors other than 1). Therefore, their Least Common Denominator (LCD) is simply their direct product: 20 × 21 = 420.

LCD(20, 21) = 420

Step 2

Convert to Equivalent Fractions with Common Denominator 420

Multiply the numerator and denominator of 5/20 by 21, and multiply the numerator and denominator of 11/21 by 20 so both fractions share the common base 420.

5 × 21/20 × 21 = 105/420 and 11 × 20/21 × 20 = 220/420

Step 3

Add the Numerators

Now add the numerators (105 + 220 = 325) and keep the common denominator 420 unchanged.

105 + 220/420 = 325/420

Step 4

Simplify the Fraction to Lowest Terms

Find the Greatest Common Divisor (GCD) of 325 and 420, which is 5. Divide both the numerator and denominator by 5.

325 ÷ 5/420 ÷ 5 = 65/84

Step 5

Decimal & Percentage Representation

Dividing the numerator 65 by denominator 84 produces a repeating decimal (approximately 0.77381, or 77.381%).

65 ÷ 84 = 0.77381 (77.381%)

Visual Representation

The diagram below illustrates 5/20 plus 11/21 visually:

Summary & Alternative Representations

Property / Format	Value
Lowest Terms Fraction	`65/84`
Mixed Number Form	`65/84`
Decimal Form	`0.77381`
Percentage	`77.381%`

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Frequently Asked Questions

What is 5/20 plus 11/21 as a fraction?

5/20 + 11/21 in simplest fraction form is 65/84.

What is 5/20 plus 11/21 as a decimal?

5/20 + 11/21 converted to a decimal is 0.77381.

What is 5/20 plus 11/21 as a percentage?

5/20 + 11/21 expressed as a percentage is 77.381%.

Does 5/20 plus 11/21 result in a terminating or repeating decimal?

It results in a repeating decimal (approximately 0.77381...) because the denominator contains prime factors other than 2 and 5.