What is 23/57 plus 9/21? (Answer: 332/399)

Exact Answer

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Problem: What is 23/57 plus 9/21?
Formula / Expression: 23/57 + 9/21
Final Answer: 332/399
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Step-by-Step Solution:

Step 1: Find the Least Common Denominator (LCD)
The denominators 57 and 21 share a common factor (GCD = 3). Finding their Least Common Multiple gives an LCD of 399 (which is smaller than their product 57 × 21 = 1197, keeping the calculation simpler).
Working: LCD(57, 21) = 399

Step 2: Convert to Equivalent Fractions with Common Denominator 399
Multiply the numerator and denominator of 23/57 by 7, and multiply the numerator and denominator of 9/21 by 19 so both fractions share the common base 399.
Working: 23 × 7/57 × 7 = 161/399 and 9 × 19/21 × 19 = 171/399

Step 3: Add the Numerators
Now add the numerators (161 + 171 = 332) and keep the common denominator 399 unchanged.
Working: 161 + 171/399 = 332/399

Step 4: Check if the Fraction Can Be Simplified
The Greatest Common Divisor (GCD) of 332 and 399 is 1, confirming that 332/399 cannot be reduced further—it is already in its simplest irreducible form.
Working: 332/399

Step 5: Decimal & Percentage Representation
Dividing the numerator 332 by denominator 399 produces a repeating decimal (approximately 0.83208, or 83.208%).
Working: 332 ÷ 399 = 0.83208 (83.208%)

Key Values:
- Simplified Fraction: 332/399
- Mixed Number Form: 332/399
- Decimal Value: 0.83208
- Percentage: 83.208%

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Solved with FractionsCalc:
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23/57 + 9/21 = 332/399

Simplified Fraction

332/399

Mixed Number

Proper (332/399)

Decimal Value

0.83208

Percentage

83.208%

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Step-by-Step Solution: 23/57 + 9/21

Step 1

Find the Least Common Denominator (LCD)

The denominators 57 and 21 share a common factor (GCD = 3). Finding their Least Common Multiple gives an LCD of 399 (which is smaller than their product 57 × 21 = 1197, keeping the calculation simpler).

LCD(57, 21) = 399

Step 2

Convert to Equivalent Fractions with Common Denominator 399

Multiply the numerator and denominator of 23/57 by 7, and multiply the numerator and denominator of 9/21 by 19 so both fractions share the common base 399.

23 × 7/57 × 7 = 161/399 and 9 × 19/21 × 19 = 171/399

Step 3

Add the Numerators

Now add the numerators (161 + 171 = 332) and keep the common denominator 399 unchanged.

161 + 171/399 = 332/399

Step 4

Check if the Fraction Can Be Simplified

The Greatest Common Divisor (GCD) of 332 and 399 is 1, confirming that 332/399 cannot be reduced further—it is already in its simplest irreducible form.

332/399

Step 5

Decimal & Percentage Representation

Dividing the numerator 332 by denominator 399 produces a repeating decimal (approximately 0.83208, or 83.208%).

332 ÷ 399 = 0.83208 (83.208%)

Visual Representation

The diagram below illustrates 23/57 plus 9/21 visually:

Summary & Alternative Representations

Property / Format	Value
Lowest Terms Fraction	`332/399`
Mixed Number Form	`332/399`
Decimal Form	`0.83208`
Percentage	`83.208%`

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Frequently Asked Questions

What is 23/57 plus 9/21 as a fraction?

23/57 + 9/21 in simplest fraction form is 332/399.

What is 23/57 plus 9/21 as a decimal?

23/57 + 9/21 converted to a decimal is 0.83208.

What is 23/57 plus 9/21 as a percentage?

23/57 + 9/21 expressed as a percentage is 83.208%.

Does 23/57 plus 9/21 result in a terminating or repeating decimal?

It results in a repeating decimal (approximately 0.83208...) because the denominator contains prime factors other than 2 and 5.