What is 1/2 plus 8/9? (Answer: 25/18)

Exact Answer

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Problem: What is 1/2 plus 8/9?
Formula / Expression: 1/2 + 8/9
Final Answer: 1 7/18 (25/18)
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Step-by-Step Solution:

Step 1: Find the Least Common Denominator (LCD)
The denominators 2 and 9 are coprime (they share no common factors other than 1). Therefore, their Least Common Denominator (LCD) is simply their direct product: 2 × 9 = 18.
Working: LCD(2, 9) = 18

Step 2: Convert to Equivalent Fractions with Common Denominator 18
Multiply the numerator and denominator of 1/2 by 9, and multiply the numerator and denominator of 8/9 by 2 so both fractions share the common base 18.
Working: 1 × 9/2 × 9 = 9/18 and 8 × 2/9 × 2 = 16/18

Step 3: Add the Numerators
Now add the numerators (9 + 16 = 25) and keep the common denominator 18 unchanged.
Working: 9 + 16/18 = 25/18

Step 4: Check if the Fraction Can Be Simplified
The Greatest Common Divisor (GCD) of 25 and 18 is 1, confirming that 25/18 cannot be reduced further—it is already in its simplest irreducible form.
Working: 25/18

Step 5: Convert Improper Fraction to a Mixed Number
Since the numerator (25) is greater than the denominator (18), divide 25 by 18: it goes in 1 whole time(s) with a remainder of 7, giving the mixed number 1 7/18.
Working: 25/18 = 1 7/18

Step 6: Decimal & Percentage Representation
Dividing the numerator 25 by denominator 18 produces a repeating decimal (approximately 1.388889, or 138.8889%).
Working: 25 ÷ 18 = 1.388889 (138.8889%)

Key Values:
- Simplified Fraction: 25/18
- Mixed Number Form: 1 7/18
- Decimal Value: 1.388889
- Percentage: 138.8889%

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Solved with FractionsCalc:
https://fractionscalc.com/what-is-1-2-plus-8-9/
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1/2 + 8/9 = 25/18

Simplified Fraction

25/18

Mixed Number

1 7/18

Decimal Value

1.388889

Percentage

138.8889%

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Step-by-Step Solution: 1/2 + 8/9

Step 1

Find the Least Common Denominator (LCD)

The denominators 2 and 9 are coprime (they share no common factors other than 1). Therefore, their Least Common Denominator (LCD) is simply their direct product: 2 × 9 = 18.

LCD(2, 9) = 18

Step 2

Convert to Equivalent Fractions with Common Denominator 18

Multiply the numerator and denominator of 1/2 by 9, and multiply the numerator and denominator of 8/9 by 2 so both fractions share the common base 18.

1 × 9/2 × 9 = 9/18 and 8 × 2/9 × 2 = 16/18

Step 3

Add the Numerators

Now add the numerators (9 + 16 = 25) and keep the common denominator 18 unchanged.

9 + 16/18 = 25/18

Step 4

Check if the Fraction Can Be Simplified

The Greatest Common Divisor (GCD) of 25 and 18 is 1, confirming that 25/18 cannot be reduced further—it is already in its simplest irreducible form.

25/18

Step 5

Convert Improper Fraction to a Mixed Number

Since the numerator (25) is greater than the denominator (18), divide 25 by 18: it goes in 1 whole time(s) with a remainder of 7, giving the mixed number 1 7/18.

25/18 = 17/18

Step 6

Decimal & Percentage Representation

Dividing the numerator 25 by denominator 18 produces a repeating decimal (approximately 1.388889, or 138.8889%).

25 ÷ 18 = 1.388889 (138.8889%)

Visual Representation

The diagram below illustrates 1/2 plus 8/9 visually:

Summary & Alternative Representations

Property / Format	Value
Lowest Terms Fraction	`25/18`
Mixed Number Form	`1 7/18`
Decimal Form	`1.388889`
Percentage	`138.8889%`

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Frequently Asked Questions

What is 1/2 plus 8/9 as a fraction?

1/2 + 8/9 in simplest fraction form is 25/18 (or 1 7/18 as a mixed number).

What is 1/2 plus 8/9 as a decimal?

1/2 + 8/9 converted to a decimal is 1.388889.

What is 1/2 plus 8/9 as a percentage?

1/2 + 8/9 expressed as a percentage is 138.8889%.

How do you write 1/2 plus 8/9 as a mixed number?

Because the numerator is greater than the denominator, the improper fraction 25/18 can be written as the mixed number 1 7/18.

Does 1/2 plus 8/9 result in a terminating or repeating decimal?

It results in a repeating decimal (approximately 1.388889...) because the denominator contains prime factors other than 2 and 5.