What is 4/45 plus 4/21? (Answer: 88/315)

Exact Answer

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Problem: What is 4/45 plus 4/21?
Formula / Expression: 4/45 + 4/21
Final Answer: 88/315
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Step-by-Step Solution:

Step 1: Find the Least Common Denominator (LCD)
The denominators 45 and 21 share a common factor (GCD = 3). Finding their Least Common Multiple gives an LCD of 315 (which is smaller than their product 45 × 21 = 945, keeping the calculation simpler).
Working: LCD(45, 21) = 315

Step 2: Convert to Equivalent Fractions with Common Denominator 315
Multiply the numerator and denominator of 4/45 by 7, and multiply the numerator and denominator of 4/21 by 15 so both fractions share the common base 315.
Working: 4 × 7/45 × 7 = 28/315 and 4 × 15/21 × 15 = 60/315

Step 3: Add the Numerators
Now add the numerators (28 + 60 = 88) and keep the common denominator 315 unchanged.
Working: 28 + 60/315 = 88/315

Step 4: Check if the Fraction Can Be Simplified
The Greatest Common Divisor (GCD) of 88 and 315 is 1, confirming that 88/315 cannot be reduced further—it is already in its simplest irreducible form.
Working: 88/315

Step 5: Decimal & Percentage Representation
Dividing the numerator 88 by denominator 315 produces a repeating decimal (approximately 0.279365, or 27.9365%).
Working: 88 ÷ 315 = 0.279365 (27.9365%)

Key Values:
- Simplified Fraction: 88/315
- Mixed Number Form: 88/315
- Decimal Value: 0.279365
- Percentage: 27.9365%

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Solved with FractionsCalc:
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4/45 + 4/21 = 88/315

Simplified Fraction

88/315

Mixed Number

Proper (88/315)

Decimal Value

0.279365

Percentage

27.9365%

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Step-by-Step Solution: 4/45 + 4/21

Step 1

Find the Least Common Denominator (LCD)

The denominators 45 and 21 share a common factor (GCD = 3). Finding their Least Common Multiple gives an LCD of 315 (which is smaller than their product 45 × 21 = 945, keeping the calculation simpler).

LCD(45, 21) = 315

Step 2

Convert to Equivalent Fractions with Common Denominator 315

Multiply the numerator and denominator of 4/45 by 7, and multiply the numerator and denominator of 4/21 by 15 so both fractions share the common base 315.

4 × 7/45 × 7 = 28/315 and 4 × 15/21 × 15 = 60/315

Step 3

Add the Numerators

Now add the numerators (28 + 60 = 88) and keep the common denominator 315 unchanged.

28 + 60/315 = 88/315

Step 4

Check if the Fraction Can Be Simplified

The Greatest Common Divisor (GCD) of 88 and 315 is 1, confirming that 88/315 cannot be reduced further—it is already in its simplest irreducible form.

88/315

Step 5

Decimal & Percentage Representation

Dividing the numerator 88 by denominator 315 produces a repeating decimal (approximately 0.279365, or 27.9365%).

88 ÷ 315 = 0.279365 (27.9365%)

Visual Representation

The diagram below illustrates 4/45 plus 4/21 visually:

Summary & Alternative Representations

Property / Format	Value
Lowest Terms Fraction	`88/315`
Mixed Number Form	`88/315`
Decimal Form	`0.279365`
Percentage	`27.9365%`

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Frequently Asked Questions

What is 4/45 plus 4/21 as a fraction?

4/45 + 4/21 in simplest fraction form is 88/315.

What is 4/45 plus 4/21 as a decimal?

4/45 + 4/21 converted to a decimal is 0.279365.

What is 4/45 plus 4/21 as a percentage?

4/45 + 4/21 expressed as a percentage is 27.9365%.

Does 4/45 plus 4/21 result in a terminating or repeating decimal?

It results in a repeating decimal (approximately 0.279365...) because the denominator contains prime factors other than 2 and 5.