What is 5/8 plus 8/9? (Answer: 109/72)

Exact Answer

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Problem: What is 5/8 plus 8/9?
Formula / Expression: 5/8 + 8/9
Final Answer: 1 37/72 (109/72)
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Step-by-Step Solution:

Step 1: Find the Least Common Denominator (LCD)
The denominators 8 and 9 are coprime (they share no common factors other than 1). Therefore, their Least Common Denominator (LCD) is simply their direct product: 8 × 9 = 72.
Working: LCD(8, 9) = 72

Step 2: Convert to Equivalent Fractions with Common Denominator 72
Multiply the numerator and denominator of 5/8 by 9, and multiply the numerator and denominator of 8/9 by 8 so both fractions share the common base 72.
Working: 5 × 9/8 × 9 = 45/72 and 8 × 8/9 × 8 = 64/72

Step 3: Add the Numerators
Now add the numerators (45 + 64 = 109) and keep the common denominator 72 unchanged.
Working: 45 + 64/72 = 109/72

Step 4: Check if the Fraction Can Be Simplified
The Greatest Common Divisor (GCD) of 109 and 72 is 1, confirming that 109/72 cannot be reduced further—it is already in its simplest irreducible form.
Working: 109/72

Step 5: Convert Improper Fraction to a Mixed Number
Since the numerator (109) is greater than the denominator (72), divide 109 by 72: it goes in 1 whole time(s) with a remainder of 37, giving the mixed number 1 37/72.
Working: 109/72 = 1 37/72

Step 6: Decimal & Percentage Representation
Dividing the numerator 109 by denominator 72 produces a repeating decimal (approximately 1.513889, or 151.3889%).
Working: 109 ÷ 72 = 1.513889 (151.3889%)

Key Values:
- Simplified Fraction: 109/72
- Mixed Number Form: 1 37/72
- Decimal Value: 1.513889
- Percentage: 151.3889%

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Solved with FractionsCalc:
https://fractionscalc.com/what-is-5-8-plus-8-9/
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5/8 + 8/9 = 109/72

Simplified Fraction

109/72

Mixed Number

1 37/72

Decimal Value

1.513889

Percentage

151.3889%

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Step-by-Step Solution: 5/8 + 8/9

Step 1

Find the Least Common Denominator (LCD)

The denominators 8 and 9 are coprime (they share no common factors other than 1). Therefore, their Least Common Denominator (LCD) is simply their direct product: 8 × 9 = 72.

LCD(8, 9) = 72

Step 2

Convert to Equivalent Fractions with Common Denominator 72

Multiply the numerator and denominator of 5/8 by 9, and multiply the numerator and denominator of 8/9 by 8 so both fractions share the common base 72.

5 × 9/8 × 9 = 45/72 and 8 × 8/9 × 8 = 64/72

Step 3

Add the Numerators

Now add the numerators (45 + 64 = 109) and keep the common denominator 72 unchanged.

45 + 64/72 = 109/72

Step 4

Check if the Fraction Can Be Simplified

The Greatest Common Divisor (GCD) of 109 and 72 is 1, confirming that 109/72 cannot be reduced further—it is already in its simplest irreducible form.

109/72

Step 5

Convert Improper Fraction to a Mixed Number

Since the numerator (109) is greater than the denominator (72), divide 109 by 72: it goes in 1 whole time(s) with a remainder of 37, giving the mixed number 1 37/72.

109/72 = 137/72

Step 6

Decimal & Percentage Representation

Dividing the numerator 109 by denominator 72 produces a repeating decimal (approximately 1.513889, or 151.3889%).

109 ÷ 72 = 1.513889 (151.3889%)

Visual Representation

The diagram below illustrates 5/8 plus 8/9 visually:

Summary & Alternative Representations

Property / Format	Value
Lowest Terms Fraction	`109/72`
Mixed Number Form	`1 37/72`
Decimal Form	`1.513889`
Percentage	`151.3889%`

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Frequently Asked Questions

What is 5/8 plus 8/9 as a fraction?

5/8 + 8/9 in simplest fraction form is 109/72 (or 1 37/72 as a mixed number).

What is 5/8 plus 8/9 as a decimal?

5/8 + 8/9 converted to a decimal is 1.513889.

What is 5/8 plus 8/9 as a percentage?

5/8 + 8/9 expressed as a percentage is 151.3889%.

How do you write 5/8 plus 8/9 as a mixed number?

Because the numerator is greater than the denominator, the improper fraction 109/72 can be written as the mixed number 1 37/72.

Does 5/8 plus 8/9 result in a terminating or repeating decimal?

It results in a repeating decimal (approximately 1.513889...) because the denominator contains prime factors other than 2 and 5.