What is 10/21 plus 15/21?
10/21 plus 15/21 equals 25/21 (or 1 4/21 as a mixed number) (or 1.190476 in decimal form). Learn the step-by-step solution to add 10/21 and 15/21 using Least Common Denominator and simplification.
Exact Answer
10/21 + 15/21 = 25/21
Simplified Fraction
25/21
Mixed Number
1 4/21
Decimal Value
1.190476
Percentage
119.0476%
Step-by-Step Solution: 10/21 + 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.
10/21 + 15/21
Step 2
Add the Numerators
Now add the numerators (10 + 15 = 25) and keep the common denominator 21 unchanged.
10 + 15/21 = 25/21
Step 3
Check if the Fraction Can Be Simplified
The Greatest Common Divisor (GCD) of 25 and 21 is 1, confirming that 25/21 cannot be reduced further—it is already in its simplest irreducible form.
25/21
Step 4
Convert Improper Fraction to a Mixed Number
Since the numerator (25) is greater than the denominator (21), divide 25 by 21: it goes in 1 whole time(s) with a remainder of 4, giving the mixed number 1 4/21.
25/21 = 14/21
Step 5
Decimal & Percentage Representation
Dividing the numerator 25 by denominator 21 produces a repeating decimal (approximately 1.190476, or 119.0476%).
25 ÷ 21 = 1.190476 (119.0476%)
Visual Representation
The diagram below illustrates 10/21 plus 15/21 visually:
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Summary & Alternative Representations
| Property / Format | Value |
|---|---|
| Lowest Terms Fraction | 25/21 |
| Mixed Number Form | 1 4/21 |
| Decimal Form | 1.190476 |
| Percentage | 119.0476% |
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Frequently Asked Questions
What is 10/21 plus 15/21 as a fraction?
10/21 + 15/21 in simplest fraction form is 25/21 (or 1 4/21 as a mixed number).
What is 10/21 plus 15/21 as a decimal?
10/21 + 15/21 converted to a decimal is 1.190476.
What is 10/21 plus 15/21 as a percentage?
10/21 + 15/21 expressed as a percentage is 119.0476%.
How do you write 10/21 plus 15/21 as a mixed number?
Because the numerator is greater than the denominator, the improper fraction 25/21 can be written as the mixed number 1 4/21.
Does 10/21 plus 15/21 result in a terminating or repeating decimal?
It results in a repeating decimal (approximately 1.190476...) because the denominator contains prime factors other than 2 and 5.