What is 2/15 plus 15/21? (Answer: 89/105)

Exact Answer

==================================================
Problem: What is 2/15 plus 15/21?
Formula / Expression: 2/15 + 15/21
Final Answer: 89/105
==================================================

Step-by-Step Solution:

Step 1: Find the Least Common Denominator (LCD)
The denominators 15 and 21 share a common factor (GCD = 3). Finding their Least Common Multiple gives an LCD of 105 (which is smaller than their product 15 × 21 = 315, keeping the calculation simpler).
Working: LCD(15, 21) = 105

Step 2: Convert to Equivalent Fractions with Common Denominator 105
Multiply the numerator and denominator of 2/15 by 7, and multiply the numerator and denominator of 15/21 by 5 so both fractions share the common base 105.
Working: 2 × 7/15 × 7 = 14/105 and 15 × 5/21 × 5 = 75/105

Step 3: Add the Numerators
Now add the numerators (14 + 75 = 89) and keep the common denominator 105 unchanged.
Working: 14 + 75/105 = 89/105

Step 4: Check if the Fraction Can Be Simplified
The Greatest Common Divisor (GCD) of 89 and 105 is 1, confirming that 89/105 cannot be reduced further—it is already in its simplest irreducible form.
Working: 89/105

Step 5: Decimal & Percentage Representation
Dividing the numerator 89 by denominator 105 produces a repeating decimal (approximately 0.847619, or 84.7619%).
Working: 89 ÷ 105 = 0.847619 (84.7619%)

Key Values:
- Simplified Fraction: 89/105
- Mixed Number Form: 89/105
- Decimal Value: 0.847619
- Percentage: 84.7619%

--------------------------------------------------
Solved with FractionsCalc:
https://fractionscalc.com/what-is-2-15-plus-15-21/
==================================================

2/15 + 15/21 = 89/105

Simplified Fraction

89/105

Mixed Number

Proper (89/105)

Decimal Value

0.847619

Percentage

84.7619%

Reduce / Convert Fraction:

Convert Fraction:

Enter Decimal Number:

Enter Percentage: %

What is % of

From Value: To Value:

Simplify Ratio: :

Switch to Proportion / Missing X Solver (A/B = C/D) →

Enter 3 known numbers and leave 1 empty (or type x) to solve:

← Switch to Ratio Simplifier (A:B)

Provide any 2 values below to calculate the remaining:

Price before discount

Discount

Price after discount

You saved

+ Add Sales Tax & Extra Coupon (Optional)

Sales Tax: % Extra Off: %

Provide any 2 values below to calculate the remaining:

Cost

Markup

REVENUE

Gross Profit

Profit Margin

Bill Subtotal

Tip Percentage

Split (People)

👥

Quick Tip:

Total Bill

Split Between

👥

Tip % (Optional)

Include Tip:

Total Price

Quantity

Unit of Measure

← Discount & Sales Tax • Ratio Simplifier (A:B) →

First Number: Second Number:

Find All Factors of:

Dividend: ÷ Divisor:

Number to Round: To Nearest:

Method: Standard (5+ ↑) Always Up (Ceil) Always Down (Floor)

Presets:

√ Square Root of: OR Power (x^y): ^{^}

x² + x + = 0

Number (n! & log):

Circle Radius (r):

Side a: Side b:

Angle (Degrees): °

Numbers (comma separated):

Total Items (n): Choose (r):

Decimal Number:

Number (1–3999):

Step-by-Step Solution: 2/15 + 15/21

Step 1

Find the Least Common Denominator (LCD)

The denominators 15 and 21 share a common factor (GCD = 3). Finding their Least Common Multiple gives an LCD of 105 (which is smaller than their product 15 × 21 = 315, keeping the calculation simpler).

LCD(15, 21) = 105

Step 2

Convert to Equivalent Fractions with Common Denominator 105

Multiply the numerator and denominator of 2/15 by 7, and multiply the numerator and denominator of 15/21 by 5 so both fractions share the common base 105.

2 × 7/15 × 7 = 14/105 and 15 × 5/21 × 5 = 75/105

Step 3

Add the Numerators

Now add the numerators (14 + 75 = 89) and keep the common denominator 105 unchanged.

14 + 75/105 = 89/105

Step 4

Check if the Fraction Can Be Simplified

The Greatest Common Divisor (GCD) of 89 and 105 is 1, confirming that 89/105 cannot be reduced further—it is already in its simplest irreducible form.

89/105

Step 5

Decimal & Percentage Representation

Dividing the numerator 89 by denominator 105 produces a repeating decimal (approximately 0.847619, or 84.7619%).

89 ÷ 105 = 0.847619 (84.7619%)

Visual Representation

The diagram below illustrates 2/15 plus 15/21 visually:

Summary & Alternative Representations

Property / Format	Value
Lowest Terms Fraction	`89/105`
Mixed Number Form	`89/105`
Decimal Form	`0.847619`
Percentage	`84.7619%`

Was this solution helpful?

Help us improve our free step-by-step tools

Frequently Asked Questions

What is 2/15 plus 15/21 as a fraction?

2/15 + 15/21 in simplest fraction form is 89/105.

What is 2/15 plus 15/21 as a decimal?

2/15 + 15/21 converted to a decimal is 0.847619.

What is 2/15 plus 15/21 as a percentage?

2/15 + 15/21 expressed as a percentage is 84.7619%.

Does 2/15 plus 15/21 result in a terminating or repeating decimal?

It results in a repeating decimal (approximately 0.847619...) because the denominator contains prime factors other than 2 and 5.