The decimal 0.8 appears frequently in everyday life — from percentages and grades to measurements and financial calculations. While decimals are convenient, many math problems and real-world situations work better when values are written as fractions.
So let’s answer the question clearly:
What is 0.8 as a fraction, and how do you simplify it correctly?
Why Convert 0.8 into a Fraction?
Converting 0.8 into a fraction is helpful when:
- Solving math equations involving fractions
- Working with ratios or proportions
- Avoiding rounding errors
- Teaching foundational math concepts
- Interpreting measurements more easily
Fractions often make values easier to visualize and compare.
Step 1: Write 0.8 as a Fraction
The decimal 0.8 has one digit after the decimal point, which means it represents eight tenths.
So it can be written as:
0.8 = 8 / 10
At this stage, the fraction is correct but not yet simplified.
Step 2: Simplify the Fraction
To simplify 8 / 10, find the greatest common divisor (GCD) of the numerator and denominator.
Factors of 8:
1, 2, 4, 8
Factors of 10:
1, 2, 5, 10
The greatest common divisor is 2.
Now divide both numbers by 2:
- 8 ÷ 2 = 4
- 10 ÷ 2 = 5
This gives the simplified fraction:
4 / 5
✅ Final Simplified Answer
0.8 as a fraction = 4 / 5
Step 3: Verify the Fraction
It’s always a good idea to verify your answer.
Decimal Check
Divide the numerator by the denominator:
4 ÷ 5 = 0.8
✔ This confirms the conversion is correct.
Cross-Multiplication Check
- 8 × 5 = 40
- 4 × 10 = 40
✔ Both sides are equal, confirming the fraction is accurate.
Is 4/5 the Simplest Form?
Yes.
The numbers 4 and 5 share no common factors other than 1, so 4/5 is already in its simplest form.
Real-Life Examples of 0.8 as a Fraction
📊 Percentages
- 0.8 = 80%
- Equivalent to 4 out of 5
📚 Grades & Scores
- Scoring 0.8 on a test means 4/5 correct
- Often considered a strong or passing score
📏 Measurements
- 0.8 meters = 4/5 of a meter
- Common in construction and scaling
💰 Finance
- Paying 0.8 of a bill means covering 80% of the total amount
Common Mistakes to Avoid
- ❌ Leaving the answer as 8/10 without simplifying
- ❌ Confusing 0.8 with 2/3 (they are not equal)
- ❌ Writing 0.8 as 80/100 and stopping there
Always simplify fractions unless instructed otherwise.
FAQs: 0.8 as a Fraction
What is 0.8 as a fraction in simplest form?
0.8 = 4 / 5
Is 0.8 the same as 4/5?
Yes. They represent the exact same value.
Can 0.8 be written as a percentage?
Yes.
0.8 equals 80%.
Is 0.8 a rational number?
Yes. It can be expressed as a fraction of two integers.
Is 0.8 a terminating decimal?
Yes. It ends after one decimal place.
✅ Final Answer
What is 0.8 as a fraction?
0.8 = 4 / 5
Key Takeaway
To convert 0.8 into a fraction:
- Write it as 8 / 10
- Simplify by dividing by 2
- Arrive at 4 / 5
This same method applies to any decimal with one decimal place, making it a reliable and reusable math skill.
You may also find these core fraction guides helpful: