What is 9/60 plus 9/21? (Answer: 81/140)

Exact Answer

==================================================
Problem: What is 9/60 plus 9/21?
Formula / Expression: 9/60 + 9/21
Final Answer: 81/140
==================================================

Step-by-Step Solution:

Step 1: Find the Least Common Denominator (LCD)
The denominators 60 and 21 share a common factor (GCD = 3). Finding their Least Common Multiple gives an LCD of 420 (which is smaller than their product 60 × 21 = 1260, keeping the calculation simpler).
Working: LCD(60, 21) = 420

Step 2: Convert to Equivalent Fractions with Common Denominator 420
Multiply the numerator and denominator of 9/60 by 7, and multiply the numerator and denominator of 9/21 by 20 so both fractions share the common base 420.
Working: 9 × 7/60 × 7 = 63/420 and 9 × 20/21 × 20 = 180/420

Step 3: Add the Numerators
Now add the numerators (63 + 180 = 243) and keep the common denominator 420 unchanged.
Working: 63 + 180/420 = 243/420

Step 4: Simplify the Fraction to Lowest Terms
Find the Greatest Common Divisor (GCD) of 243 and 420, which is 3. Divide both the numerator and denominator by 3.
Working: 243 ÷ 3/420 ÷ 3 = 81/140

Step 5: Decimal & Percentage Representation
Dividing the numerator 81 by denominator 140 produces a repeating decimal (approximately 0.578571, or 57.8571%).
Working: 81 ÷ 140 = 0.578571 (57.8571%)

Key Values:
- Simplified Fraction: 81/140
- Mixed Number Form: 81/140
- Decimal Value: 0.578571
- Percentage: 57.8571%

--------------------------------------------------
Solved with FractionsCalc:
https://fractionscalc.com/what-is-9-60-plus-9-21/
==================================================

9/60 + 9/21 = 81/140

Simplified Fraction

81/140

Mixed Number

Proper (81/140)

Decimal Value

0.578571

Percentage

57.8571%

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: 9/60 + 9/21

Step 1

Find the Least Common Denominator (LCD)

The denominators 60 and 21 share a common factor (GCD = 3). Finding their Least Common Multiple gives an LCD of 420 (which is smaller than their product 60 × 21 = 1260, keeping the calculation simpler).

LCD(60, 21) = 420

Step 2

Convert to Equivalent Fractions with Common Denominator 420

Multiply the numerator and denominator of 9/60 by 7, and multiply the numerator and denominator of 9/21 by 20 so both fractions share the common base 420.

9 × 7/60 × 7 = 63/420 and 9 × 20/21 × 20 = 180/420

Step 3

Add the Numerators

Now add the numerators (63 + 180 = 243) and keep the common denominator 420 unchanged.

63 + 180/420 = 243/420

Step 4

Simplify the Fraction to Lowest Terms

Find the Greatest Common Divisor (GCD) of 243 and 420, which is 3. Divide both the numerator and denominator by 3.

243 ÷ 3/420 ÷ 3 = 81/140

Step 5

Decimal & Percentage Representation

Dividing the numerator 81 by denominator 140 produces a repeating decimal (approximately 0.578571, or 57.8571%).

81 ÷ 140 = 0.578571 (57.8571%)

Visual Representation

The diagram below illustrates 9/60 plus 9/21 visually:

Summary & Alternative Representations

Property / Format	Value
Lowest Terms Fraction	`81/140`
Mixed Number Form	`81/140`
Decimal Form	`0.578571`
Percentage	`57.8571%`

Was this solution helpful?

Help us improve our free step-by-step tools

Frequently Asked Questions

What is 9/60 plus 9/21 as a fraction?

9/60 + 9/21 in simplest fraction form is 81/140.

What is 9/60 plus 9/21 as a decimal?

9/60 + 9/21 converted to a decimal is 0.578571.

What is 9/60 plus 9/21 as a percentage?

9/60 + 9/21 expressed as a percentage is 57.8571%.

Does 9/60 plus 9/21 result in a terminating or repeating decimal?

It results in a repeating decimal (approximately 0.578571...) because the denominator contains prime factors other than 2 and 5.