What is 4/21 plus 15/21?
4/21 plus 15/21 equals 19/21 (or 0.904762 in decimal form). Learn the step-by-step solution to add 4/21 and 15/21 using Least Common Denominator and simplification.
Exact Answer
4/21 + 15/21 = 19/21
Simplified Fraction
19/21
Mixed Number
Proper (19/21)
Decimal Value
0.904762
Percentage
90.4762%
Step-by-Step Solution: 4/21 + 15/21
Step 1
Check the Denominators (Like Fractions)
Both fractions already share the identical denominator (21). Because these are like fractions, no conversion to a common denominator is required—we directly add their numerators while keeping the denominator 21.
4/21 + 15/21
Step 2
Add the Numerators
Now add the numerators (4 + 15 = 19) and keep the common denominator 21 unchanged.
4 + 15/21 = 19/21
Step 3
Check if the Fraction Can Be Simplified
The Greatest Common Divisor (GCD) of 19 and 21 is 1, confirming that 19/21 cannot be reduced further—it is already in its simplest irreducible form.
19/21
Step 4
Decimal & Percentage Representation
Dividing the numerator 19 by denominator 21 produces a repeating decimal (approximately 0.904762, or 90.4762%).
19 ÷ 21 = 0.904762 (90.4762%)
Visual Representation
The diagram below illustrates 4/21 plus 15/21 visually:
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Summary & Alternative Representations
| Property / Format | Value |
|---|---|
| Lowest Terms Fraction | 19/21 |
| Mixed Number Form | 19/21 |
| Decimal Form | 0.904762 |
| Percentage | 90.4762% |
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Frequently Asked Questions
What is 4/21 plus 15/21 as a fraction?
4/21 + 15/21 in simplest fraction form is 19/21.
What is 4/21 plus 15/21 as a decimal?
4/21 + 15/21 converted to a decimal is 0.904762.
What is 4/21 plus 15/21 as a percentage?
4/21 + 15/21 expressed as a percentage is 90.4762%.
Does 4/21 plus 15/21 result in a terminating or repeating decimal?
It results in a repeating decimal (approximately 0.904762...) because the denominator contains prime factors other than 2 and 5.