What is 8/33 plus 9/21? (Answer: 155/231)

Exact Answer

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Problem: What is 8/33 plus 9/21?
Formula / Expression: 8/33 + 9/21
Final Answer: 155/231
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Step-by-Step Solution:

Step 1: Find the Least Common Denominator (LCD)
The denominators 33 and 21 share a common factor (GCD = 3). Finding their Least Common Multiple gives an LCD of 231 (which is smaller than their product 33 × 21 = 693, keeping the calculation simpler).
Working: LCD(33, 21) = 231

Step 2: Convert to Equivalent Fractions with Common Denominator 231
Multiply the numerator and denominator of 8/33 by 7, and multiply the numerator and denominator of 9/21 by 11 so both fractions share the common base 231.
Working: 8 × 7/33 × 7 = 56/231 and 9 × 11/21 × 11 = 99/231

Step 3: Add the Numerators
Now add the numerators (56 + 99 = 155) and keep the common denominator 231 unchanged.
Working: 56 + 99/231 = 155/231

Step 4: Check if the Fraction Can Be Simplified
The Greatest Common Divisor (GCD) of 155 and 231 is 1, confirming that 155/231 cannot be reduced further—it is already in its simplest irreducible form.
Working: 155/231

Step 5: Decimal & Percentage Representation
Dividing the numerator 155 by denominator 231 produces a repeating decimal (approximately 0.670996, or 67.0996%).
Working: 155 ÷ 231 = 0.670996 (67.0996%)

Key Values:
- Simplified Fraction: 155/231
- Mixed Number Form: 155/231
- Decimal Value: 0.670996
- Percentage: 67.0996%

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Solved with FractionsCalc:
https://fractionscalc.com/what-is-8-33-plus-9-21/
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8/33 + 9/21 = 155/231

Simplified Fraction

155/231

Mixed Number

Proper (155/231)

Decimal Value

0.670996

Percentage

67.0996%

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Step-by-Step Solution: 8/33 + 9/21

Step 1

Find the Least Common Denominator (LCD)

The denominators 33 and 21 share a common factor (GCD = 3). Finding their Least Common Multiple gives an LCD of 231 (which is smaller than their product 33 × 21 = 693, keeping the calculation simpler).

LCD(33, 21) = 231

Step 2

Convert to Equivalent Fractions with Common Denominator 231

Multiply the numerator and denominator of 8/33 by 7, and multiply the numerator and denominator of 9/21 by 11 so both fractions share the common base 231.

8 × 7/33 × 7 = 56/231 and 9 × 11/21 × 11 = 99/231

Step 3

Add the Numerators

Now add the numerators (56 + 99 = 155) and keep the common denominator 231 unchanged.

56 + 99/231 = 155/231

Step 4

Check if the Fraction Can Be Simplified

The Greatest Common Divisor (GCD) of 155 and 231 is 1, confirming that 155/231 cannot be reduced further—it is already in its simplest irreducible form.

155/231

Step 5

Decimal & Percentage Representation

Dividing the numerator 155 by denominator 231 produces a repeating decimal (approximately 0.670996, or 67.0996%).

155 ÷ 231 = 0.670996 (67.0996%)

Visual Representation

The diagram below illustrates 8/33 plus 9/21 visually:

Summary & Alternative Representations

Property / Format	Value
Lowest Terms Fraction	`155/231`
Mixed Number Form	`155/231`
Decimal Form	`0.670996`
Percentage	`67.0996%`

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Frequently Asked Questions

What is 8/33 plus 9/21 as a fraction?

8/33 + 9/21 in simplest fraction form is 155/231.

What is 8/33 plus 9/21 as a decimal?

8/33 + 9/21 converted to a decimal is 0.670996.

What is 8/33 plus 9/21 as a percentage?

8/33 + 9/21 expressed as a percentage is 67.0996%.

Does 8/33 plus 9/21 result in a terminating or repeating decimal?

It results in a repeating decimal (approximately 0.670996...) because the denominator contains prime factors other than 2 and 5.