What is 7/10 plus 8/9? (Answer: 143/90)

Exact Answer

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Problem: What is 7/10 plus 8/9?
Formula / Expression: 7/10 + 8/9
Final Answer: 1 53/90 (143/90)
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Step-by-Step Solution:

Step 1: Find the Least Common Denominator (LCD)
The denominators 10 and 9 are coprime (they share no common factors other than 1). Therefore, their Least Common Denominator (LCD) is simply their direct product: 10 × 9 = 90.
Working: LCD(10, 9) = 90

Step 2: Convert to Equivalent Fractions with Common Denominator 90
Multiply the numerator and denominator of 7/10 by 9, and multiply the numerator and denominator of 8/9 by 10 so both fractions share the common base 90.
Working: 7 × 9/10 × 9 = 63/90 and 8 × 10/9 × 10 = 80/90

Step 3: Add the Numerators
Now add the numerators (63 + 80 = 143) and keep the common denominator 90 unchanged.
Working: 63 + 80/90 = 143/90

Step 4: Check if the Fraction Can Be Simplified
The Greatest Common Divisor (GCD) of 143 and 90 is 1, confirming that 143/90 cannot be reduced further—it is already in its simplest irreducible form.
Working: 143/90

Step 5: Convert Improper Fraction to a Mixed Number
Since the numerator (143) is greater than the denominator (90), divide 143 by 90: it goes in 1 whole time(s) with a remainder of 53, giving the mixed number 1 53/90.
Working: 143/90 = 1 53/90

Step 6: Decimal & Percentage Representation
Dividing the numerator 143 by denominator 90 produces a repeating decimal (approximately 1.588889, or 158.8889%).
Working: 143 ÷ 90 = 1.588889 (158.8889%)

Key Values:
- Simplified Fraction: 143/90
- Mixed Number Form: 1 53/90
- Decimal Value: 1.588889
- Percentage: 158.8889%

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Solved with FractionsCalc:
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7/10 + 8/9 = 143/90

Simplified Fraction

143/90

Mixed Number

1 53/90

Decimal Value

1.588889

Percentage

158.8889%

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Step-by-Step Solution: 7/10 + 8/9

Step 1

Find the Least Common Denominator (LCD)

The denominators 10 and 9 are coprime (they share no common factors other than 1). Therefore, their Least Common Denominator (LCD) is simply their direct product: 10 × 9 = 90.

LCD(10, 9) = 90

Step 2

Convert to Equivalent Fractions with Common Denominator 90

Multiply the numerator and denominator of 7/10 by 9, and multiply the numerator and denominator of 8/9 by 10 so both fractions share the common base 90.

7 × 9/10 × 9 = 63/90 and 8 × 10/9 × 10 = 80/90

Step 3

Add the Numerators

Now add the numerators (63 + 80 = 143) and keep the common denominator 90 unchanged.

63 + 80/90 = 143/90

Step 4

Check if the Fraction Can Be Simplified

The Greatest Common Divisor (GCD) of 143 and 90 is 1, confirming that 143/90 cannot be reduced further—it is already in its simplest irreducible form.

143/90

Step 5

Convert Improper Fraction to a Mixed Number

Since the numerator (143) is greater than the denominator (90), divide 143 by 90: it goes in 1 whole time(s) with a remainder of 53, giving the mixed number 1 53/90.

143/90 = 153/90

Step 6

Decimal & Percentage Representation

Dividing the numerator 143 by denominator 90 produces a repeating decimal (approximately 1.588889, or 158.8889%).

143 ÷ 90 = 1.588889 (158.8889%)

Visual Representation

The diagram below illustrates 7/10 plus 8/9 visually:

Summary & Alternative Representations

Property / Format	Value
Lowest Terms Fraction	`143/90`
Mixed Number Form	`1 53/90`
Decimal Form	`1.588889`
Percentage	`158.8889%`

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Frequently Asked Questions

What is 7/10 plus 8/9 as a fraction?

7/10 + 8/9 in simplest fraction form is 143/90 (or 1 53/90 as a mixed number).

What is 7/10 plus 8/9 as a decimal?

7/10 + 8/9 converted to a decimal is 1.588889.

What is 7/10 plus 8/9 as a percentage?

7/10 + 8/9 expressed as a percentage is 158.8889%.

How do you write 7/10 plus 8/9 as a mixed number?

Because the numerator is greater than the denominator, the improper fraction 143/90 can be written as the mixed number 1 53/90.

Does 7/10 plus 8/9 result in a terminating or repeating decimal?

It results in a repeating decimal (approximately 1.588889...) because the denominator contains prime factors other than 2 and 5.