What is 12/49 plus 7/21? (Answer: 85/147)

Exact Answer

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Problem: What is 12/49 plus 7/21?
Formula / Expression: 12/49 + 7/21
Final Answer: 85/147
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Step-by-Step Solution:

Step 1: Find the Least Common Denominator (LCD)
The denominators 49 and 21 share a common factor (GCD = 7). Finding their Least Common Multiple gives an LCD of 147 (which is smaller than their product 49 × 21 = 1029, keeping the calculation simpler).
Working: LCD(49, 21) = 147

Step 2: Convert to Equivalent Fractions with Common Denominator 147
Multiply the numerator and denominator of 12/49 by 3, and multiply the numerator and denominator of 7/21 by 7 so both fractions share the common base 147.
Working: 12 × 3/49 × 3 = 36/147 and 7 × 7/21 × 7 = 49/147

Step 3: Add the Numerators
Now add the numerators (36 + 49 = 85) and keep the common denominator 147 unchanged.
Working: 36 + 49/147 = 85/147

Step 4: Check if the Fraction Can Be Simplified
The Greatest Common Divisor (GCD) of 85 and 147 is 1, confirming that 85/147 cannot be reduced further—it is already in its simplest irreducible form.
Working: 85/147

Step 5: Decimal & Percentage Representation
Dividing the numerator 85 by denominator 147 produces a repeating decimal (approximately 0.578231, or 57.8231%).
Working: 85 ÷ 147 = 0.578231 (57.8231%)

Key Values:
- Simplified Fraction: 85/147
- Mixed Number Form: 85/147
- Decimal Value: 0.578231
- Percentage: 57.8231%

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Solved with FractionsCalc:
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12/49 + 7/21 = 85/147

Simplified Fraction

85/147

Mixed Number

Proper (85/147)

Decimal Value

0.578231

Percentage

57.8231%

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Step-by-Step Solution: 12/49 + 7/21

Step 1

Find the Least Common Denominator (LCD)

The denominators 49 and 21 share a common factor (GCD = 7). Finding their Least Common Multiple gives an LCD of 147 (which is smaller than their product 49 × 21 = 1029, keeping the calculation simpler).

LCD(49, 21) = 147

Step 2

Convert to Equivalent Fractions with Common Denominator 147

Multiply the numerator and denominator of 12/49 by 3, and multiply the numerator and denominator of 7/21 by 7 so both fractions share the common base 147.

12 × 3/49 × 3 = 36/147 and 7 × 7/21 × 7 = 49/147

Step 3

Add the Numerators

Now add the numerators (36 + 49 = 85) and keep the common denominator 147 unchanged.

36 + 49/147 = 85/147

Step 4

Check if the Fraction Can Be Simplified

The Greatest Common Divisor (GCD) of 85 and 147 is 1, confirming that 85/147 cannot be reduced further—it is already in its simplest irreducible form.

85/147

Step 5

Decimal & Percentage Representation

Dividing the numerator 85 by denominator 147 produces a repeating decimal (approximately 0.578231, or 57.8231%).

85 ÷ 147 = 0.578231 (57.8231%)

Visual Representation

The diagram below illustrates 12/49 plus 7/21 visually:

Summary & Alternative Representations

Property / Format	Value
Lowest Terms Fraction	`85/147`
Mixed Number Form	`85/147`
Decimal Form	`0.578231`
Percentage	`57.8231%`

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Frequently Asked Questions

What is 12/49 plus 7/21 as a fraction?

12/49 + 7/21 in simplest fraction form is 85/147.

What is 12/49 plus 7/21 as a decimal?

12/49 + 7/21 converted to a decimal is 0.578231.

What is 12/49 plus 7/21 as a percentage?

12/49 + 7/21 expressed as a percentage is 57.8231%.

Does 12/49 plus 7/21 result in a terminating or repeating decimal?

It results in a repeating decimal (approximately 0.578231...) because the denominator contains prime factors other than 2 and 5.