What is 15/36 plus 10/21? (Answer: 25/28)

Exact Answer

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Problem: What is 15/36 plus 10/21?
Formula / Expression: 15/36 + 10/21
Final Answer: 25/28
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Step-by-Step Solution:

Step 1: Find the Least Common Denominator (LCD)
The denominators 36 and 21 share a common factor (GCD = 3). Finding their Least Common Multiple gives an LCD of 252 (which is smaller than their product 36 × 21 = 756, keeping the calculation simpler).
Working: LCD(36, 21) = 252

Step 2: Convert to Equivalent Fractions with Common Denominator 252
Multiply the numerator and denominator of 15/36 by 7, and multiply the numerator and denominator of 10/21 by 12 so both fractions share the common base 252.
Working: 15 × 7/36 × 7 = 105/252 and 10 × 12/21 × 12 = 120/252

Step 3: Add the Numerators
Now add the numerators (105 + 120 = 225) and keep the common denominator 252 unchanged.
Working: 105 + 120/252 = 225/252

Step 4: Simplify the Fraction to Lowest Terms
Find the Greatest Common Divisor (GCD) of 225 and 252, which is 9. Divide both the numerator and denominator by 9.
Working: 225 ÷ 9/252 ÷ 9 = 25/28

Step 5: Decimal & Percentage Representation
Dividing the numerator 25 by denominator 28 produces a repeating decimal (approximately 0.892857, or 89.2857%).
Working: 25 ÷ 28 = 0.892857 (89.2857%)

Key Values:
- Simplified Fraction: 25/28
- Mixed Number Form: 25/28
- Decimal Value: 0.892857
- Percentage: 89.2857%

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Solved with FractionsCalc:
https://fractionscalc.com/what-is-15-36-plus-10-21/
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15/36 + 10/21 = 25/28

Simplified Fraction

25/28

Mixed Number

Proper (25/28)

Decimal Value

0.892857

Percentage

89.2857%

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Step-by-Step Solution: 15/36 + 10/21

Step 1

Find the Least Common Denominator (LCD)

The denominators 36 and 21 share a common factor (GCD = 3). Finding their Least Common Multiple gives an LCD of 252 (which is smaller than their product 36 × 21 = 756, keeping the calculation simpler).

LCD(36, 21) = 252

Step 2

Convert to Equivalent Fractions with Common Denominator 252

Multiply the numerator and denominator of 15/36 by 7, and multiply the numerator and denominator of 10/21 by 12 so both fractions share the common base 252.

15 × 7/36 × 7 = 105/252 and 10 × 12/21 × 12 = 120/252

Step 3

Add the Numerators

Now add the numerators (105 + 120 = 225) and keep the common denominator 252 unchanged.

105 + 120/252 = 225/252

Step 4

Simplify the Fraction to Lowest Terms

Find the Greatest Common Divisor (GCD) of 225 and 252, which is 9. Divide both the numerator and denominator by 9.

225 ÷ 9/252 ÷ 9 = 25/28

Step 5

Decimal & Percentage Representation

Dividing the numerator 25 by denominator 28 produces a repeating decimal (approximately 0.892857, or 89.2857%).

25 ÷ 28 = 0.892857 (89.2857%)

Visual Representation

The diagram below illustrates 15/36 plus 10/21 visually:

Summary & Alternative Representations

Property / Format	Value
Lowest Terms Fraction	`25/28`
Mixed Number Form	`25/28`
Decimal Form	`0.892857`
Percentage	`89.2857%`

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Frequently Asked Questions

What is 15/36 plus 10/21 as a fraction?

15/36 + 10/21 in simplest fraction form is 25/28.

What is 15/36 plus 10/21 as a decimal?

15/36 + 10/21 converted to a decimal is 0.892857.

What is 15/36 plus 10/21 as a percentage?

15/36 + 10/21 expressed as a percentage is 89.2857%.

Does 15/36 plus 10/21 result in a terminating or repeating decimal?

It results in a repeating decimal (approximately 0.892857...) because the denominator contains prime factors other than 2 and 5.