What is 4/18 plus 12/21? (Answer: 50/63)

Exact Answer

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Problem: What is 4/18 plus 12/21?
Formula / Expression: 4/18 + 12/21
Final Answer: 50/63
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Step-by-Step Solution:

Step 1: Find the Least Common Denominator (LCD)
The denominators 18 and 21 share a common factor (GCD = 3). Finding their Least Common Multiple gives an LCD of 126 (which is smaller than their product 18 × 21 = 378, keeping the calculation simpler).
Working: LCD(18, 21) = 126

Step 2: Convert to Equivalent Fractions with Common Denominator 126
Multiply the numerator and denominator of 4/18 by 7, and multiply the numerator and denominator of 12/21 by 6 so both fractions share the common base 126.
Working: 4 × 7/18 × 7 = 28/126 and 12 × 6/21 × 6 = 72/126

Step 3: Add the Numerators
Now add the numerators (28 + 72 = 100) and keep the common denominator 126 unchanged.
Working: 28 + 72/126 = 100/126

Step 4: Simplify the Fraction to Lowest Terms
Find the Greatest Common Divisor (GCD) of 100 and 126, which is 2. Divide both the numerator and denominator by 2.
Working: 100 ÷ 2/126 ÷ 2 = 50/63

Step 5: Decimal & Percentage Representation
Dividing the numerator 50 by denominator 63 produces a repeating decimal (approximately 0.793651, or 79.3651%).
Working: 50 ÷ 63 = 0.793651 (79.3651%)

Key Values:
- Simplified Fraction: 50/63
- Mixed Number Form: 50/63
- Decimal Value: 0.793651
- Percentage: 79.3651%

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Solved with FractionsCalc:
https://fractionscalc.com/what-is-4-18-plus-12-21/
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4/18 + 12/21 = 50/63

Simplified Fraction

50/63

Mixed Number

Proper (50/63)

Decimal Value

0.793651

Percentage

79.3651%

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Step-by-Step Solution: 4/18 + 12/21

Step 1

Find the Least Common Denominator (LCD)

The denominators 18 and 21 share a common factor (GCD = 3). Finding their Least Common Multiple gives an LCD of 126 (which is smaller than their product 18 × 21 = 378, keeping the calculation simpler).

LCD(18, 21) = 126

Step 2

Convert to Equivalent Fractions with Common Denominator 126

Multiply the numerator and denominator of 4/18 by 7, and multiply the numerator and denominator of 12/21 by 6 so both fractions share the common base 126.

4 × 7/18 × 7 = 28/126 and 12 × 6/21 × 6 = 72/126

Step 3

Add the Numerators

Now add the numerators (28 + 72 = 100) and keep the common denominator 126 unchanged.

28 + 72/126 = 100/126

Step 4

Simplify the Fraction to Lowest Terms

Find the Greatest Common Divisor (GCD) of 100 and 126, which is 2. Divide both the numerator and denominator by 2.

100 ÷ 2/126 ÷ 2 = 50/63

Step 5

Decimal & Percentage Representation

Dividing the numerator 50 by denominator 63 produces a repeating decimal (approximately 0.793651, or 79.3651%).

50 ÷ 63 = 0.793651 (79.3651%)

Visual Representation

The diagram below illustrates 4/18 plus 12/21 visually:

Summary & Alternative Representations

Property / Format	Value
Lowest Terms Fraction	`50/63`
Mixed Number Form	`50/63`
Decimal Form	`0.793651`
Percentage	`79.3651%`

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Frequently Asked Questions

What is 4/18 plus 12/21 as a fraction?

4/18 + 12/21 in simplest fraction form is 50/63.

What is 4/18 plus 12/21 as a decimal?

4/18 + 12/21 converted to a decimal is 0.793651.

What is 4/18 plus 12/21 as a percentage?

4/18 + 12/21 expressed as a percentage is 79.3651%.

Does 4/18 plus 12/21 result in a terminating or repeating decimal?

It results in a repeating decimal (approximately 0.793651...) because the denominator contains prime factors other than 2 and 5.