What is 2/5 plus 9/18? (Answer: 9/10)

Exact Answer

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Problem: What is 2/5 plus 9/18?
Formula / Expression: 2/5 + 9/18
Final Answer: 9/10
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Step-by-Step Solution:

Step 1: Find the Least Common Denominator (LCD)
The denominators 5 and 18 are coprime (they share no common factors other than 1). Therefore, their Least Common Denominator (LCD) is simply their direct product: 5 × 18 = 90.
Working: LCD(5, 18) = 90

Step 2: Convert to Equivalent Fractions with Common Denominator 90
Multiply the numerator and denominator of 2/5 by 18, and multiply the numerator and denominator of 9/18 by 5 so both fractions share the common base 90.
Working: 2 × 18/5 × 18 = 36/90 and 9 × 5/18 × 5 = 45/90

Step 3: Add the Numerators
Now add the numerators (36 + 45 = 81) and keep the common denominator 90 unchanged.
Working: 36 + 45/90 = 81/90

Step 4: Simplify the Fraction to Lowest Terms
Find the Greatest Common Divisor (GCD) of 81 and 90, which is 9. Divide both the numerator and denominator by 9.
Working: 81 ÷ 9/90 ÷ 9 = 9/10

Step 5: Decimal & Percentage Representation
Dividing the numerator 9 by denominator 10 yields an exact terminating decimal of 0.9 (or 90%).
Working: 9 ÷ 10 = 0.9 (90%)

Key Values:
- Simplified Fraction: 9/10
- Mixed Number Form: 9/10
- Decimal Value: 0.9
- Percentage: 90%

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Solved with FractionsCalc:
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2/5 + 9/18 = 9/10

Simplified Fraction

9/10

Mixed Number

Proper (9/10)

Decimal Value

0.9

Percentage

90%

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Step-by-Step Solution: 2/5 + 9/18

Step 1

Find the Least Common Denominator (LCD)

The denominators 5 and 18 are coprime (they share no common factors other than 1). Therefore, their Least Common Denominator (LCD) is simply their direct product: 5 × 18 = 90.

LCD(5, 18) = 90

Step 2

Convert to Equivalent Fractions with Common Denominator 90

Multiply the numerator and denominator of 2/5 by 18, and multiply the numerator and denominator of 9/18 by 5 so both fractions share the common base 90.

2 × 18/5 × 18 = 36/90 and 9 × 5/18 × 5 = 45/90

Step 3

Add the Numerators

Now add the numerators (36 + 45 = 81) and keep the common denominator 90 unchanged.

36 + 45/90 = 81/90

Step 4

Simplify the Fraction to Lowest Terms

Find the Greatest Common Divisor (GCD) of 81 and 90, which is 9. Divide both the numerator and denominator by 9.

81 ÷ 9/90 ÷ 9 = 9/10

Step 5

Decimal & Percentage Representation

Dividing the numerator 9 by denominator 10 yields an exact terminating decimal of 0.9 (or 90%).

9 ÷ 10 = 0.9 (90%)

Visual Representation

The diagram below illustrates 2/5 plus 9/18 visually:

Summary & Alternative Representations

Property / Format	Value
Lowest Terms Fraction	`9/10`
Mixed Number Form	`9/10`
Decimal Form	`0.9`
Percentage	`90%`

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Frequently Asked Questions

What is 2/5 plus 9/18 as a fraction?

2/5 + 9/18 in simplest fraction form is 9/10.

What is 2/5 plus 9/18 as a decimal?

2/5 + 9/18 converted to a decimal is 0.9.

What is 2/5 plus 9/18 as a percentage?

2/5 + 9/18 expressed as a percentage is 90%.

Does 2/5 plus 9/18 result in a terminating or repeating decimal?

It results in an exact terminating decimal (0.9) because the denominator in simplest terms contains only prime factors 2 and/or 5.