What is 4/51 plus 3/21? (Answer: 79/357)

Exact Answer

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Problem: What is 4/51 plus 3/21?
Formula / Expression: 4/51 + 3/21
Final Answer: 79/357
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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 4/51 by 7, and multiply the numerator and denominator of 3/21 by 17 so both fractions share the common base 357.
Working: 4 × 7/51 × 7 = 28/357 and 3 × 17/21 × 17 = 51/357

Step 3: Add the Numerators
Now add the numerators (28 + 51 = 79) and keep the common denominator 357 unchanged.
Working: 28 + 51/357 = 79/357

Step 4: Check if the Fraction Can Be Simplified
The Greatest Common Divisor (GCD) of 79 and 357 is 1, confirming that 79/357 cannot be reduced further—it is already in its simplest irreducible form.
Working: 79/357

Step 5: Decimal & Percentage Representation
Dividing the numerator 79 by denominator 357 produces a repeating decimal (approximately 0.221289, or 22.1289%).
Working: 79 ÷ 357 = 0.221289 (22.1289%)

Key Values:
- Simplified Fraction: 79/357
- Mixed Number Form: 79/357
- Decimal Value: 0.221289
- Percentage: 22.1289%

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Solved with FractionsCalc:
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4/51 + 3/21 = 79/357

Simplified Fraction

79/357

Mixed Number

Proper (79/357)

Decimal Value

0.221289

Percentage

22.1289%

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Step-by-Step Solution: 4/51 + 3/21

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 4/51 by 7, and multiply the numerator and denominator of 3/21 by 17 so both fractions share the common base 357.

4 × 7/51 × 7 = 28/357 and 3 × 17/21 × 17 = 51/357

Step 3

Add the Numerators

Now add the numerators (28 + 51 = 79) and keep the common denominator 357 unchanged.

28 + 51/357 = 79/357

Step 4

Check if the Fraction Can Be Simplified

The Greatest Common Divisor (GCD) of 79 and 357 is 1, confirming that 79/357 cannot be reduced further—it is already in its simplest irreducible form.

79/357

Step 5

Decimal & Percentage Representation

Dividing the numerator 79 by denominator 357 produces a repeating decimal (approximately 0.221289, or 22.1289%).

79 ÷ 357 = 0.221289 (22.1289%)

Visual Representation

The diagram below illustrates 4/51 plus 3/21 visually:

Summary & Alternative Representations

Property / Format	Value
Lowest Terms Fraction	`79/357`
Mixed Number Form	`79/357`
Decimal Form	`0.221289`
Percentage	`22.1289%`

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Frequently Asked Questions

What is 4/51 plus 3/21 as a fraction?

4/51 + 3/21 in simplest fraction form is 79/357.

What is 4/51 plus 3/21 as a decimal?

4/51 + 3/21 converted to a decimal is 0.221289.

What is 4/51 plus 3/21 as a percentage?

4/51 + 3/21 expressed as a percentage is 22.1289%.

Does 4/51 plus 3/21 result in a terminating or repeating decimal?

It results in a repeating decimal (approximately 0.221289...) because the denominator contains prime factors other than 2 and 5.