What is 9/54 plus 5/21? (Answer: 17/42)

Exact Answer

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Problem: What is 9/54 plus 5/21?
Formula / Expression: 9/54 + 5/21
Final Answer: 17/42
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Step-by-Step Solution:

Step 1: Find the Least Common Denominator (LCD)
The denominators 54 and 21 share a common factor (GCD = 3). Finding their Least Common Multiple gives an LCD of 378 (which is smaller than their product 54 × 21 = 1134, keeping the calculation simpler).
Working: LCD(54, 21) = 378

Step 2: Convert to Equivalent Fractions with Common Denominator 378
Multiply the numerator and denominator of 9/54 by 7, and multiply the numerator and denominator of 5/21 by 18 so both fractions share the common base 378.
Working: 9 × 7/54 × 7 = 63/378 and 5 × 18/21 × 18 = 90/378

Step 3: Add the Numerators
Now add the numerators (63 + 90 = 153) and keep the common denominator 378 unchanged.
Working: 63 + 90/378 = 153/378

Step 4: Simplify the Fraction to Lowest Terms
Find the Greatest Common Divisor (GCD) of 153 and 378, which is 9. Divide both the numerator and denominator by 9.
Working: 153 ÷ 9/378 ÷ 9 = 17/42

Step 5: Decimal & Percentage Representation
Dividing the numerator 17 by denominator 42 produces a repeating decimal (approximately 0.404762, or 40.4762%).
Working: 17 ÷ 42 = 0.404762 (40.4762%)

Key Values:
- Simplified Fraction: 17/42
- Mixed Number Form: 17/42
- Decimal Value: 0.404762
- Percentage: 40.4762%

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Solved with FractionsCalc:
https://fractionscalc.com/what-is-9-54-plus-5-21/
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9/54 + 5/21 = 17/42

Simplified Fraction

17/42

Mixed Number

Proper (17/42)

Decimal Value

0.404762

Percentage

40.4762%

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Step-by-Step Solution: 9/54 + 5/21

Step 1

Find the Least Common Denominator (LCD)

The denominators 54 and 21 share a common factor (GCD = 3). Finding their Least Common Multiple gives an LCD of 378 (which is smaller than their product 54 × 21 = 1134, keeping the calculation simpler).

LCD(54, 21) = 378

Step 2

Convert to Equivalent Fractions with Common Denominator 378

Multiply the numerator and denominator of 9/54 by 7, and multiply the numerator and denominator of 5/21 by 18 so both fractions share the common base 378.

9 × 7/54 × 7 = 63/378 and 5 × 18/21 × 18 = 90/378

Step 3

Add the Numerators

Now add the numerators (63 + 90 = 153) and keep the common denominator 378 unchanged.

63 + 90/378 = 153/378

Step 4

Simplify the Fraction to Lowest Terms

Find the Greatest Common Divisor (GCD) of 153 and 378, which is 9. Divide both the numerator and denominator by 9.

153 ÷ 9/378 ÷ 9 = 17/42

Step 5

Decimal & Percentage Representation

Dividing the numerator 17 by denominator 42 produces a repeating decimal (approximately 0.404762, or 40.4762%).

17 ÷ 42 = 0.404762 (40.4762%)

Visual Representation

The diagram below illustrates 9/54 plus 5/21 visually:

Summary & Alternative Representations

Property / Format	Value
Lowest Terms Fraction	`17/42`
Mixed Number Form	`17/42`
Decimal Form	`0.404762`
Percentage	`40.4762%`

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Frequently Asked Questions

What is 9/54 plus 5/21 as a fraction?

9/54 + 5/21 in simplest fraction form is 17/42.

What is 9/54 plus 5/21 as a decimal?

9/54 + 5/21 converted to a decimal is 0.404762.

What is 9/54 plus 5/21 as a percentage?

9/54 + 5/21 expressed as a percentage is 40.4762%.

Does 9/54 plus 5/21 result in a terminating or repeating decimal?

It results in a repeating decimal (approximately 0.404762...) because the denominator contains prime factors other than 2 and 5.