Mixed Numbers & Fractions FAQs
Q: What are mixed numbers and improper fractions?
Mixed Numbers: A mixed number combines a whole number and a proper fraction (where the numerator is smaller than the denominator). It represents a value greater than 1.
Example: 2 ¾ (two and three-fourths)
Improper Fractions: An improper fraction is a fraction where the numerator (top number) is greater than or equal to the denominator (bottom number). It also represents a value greater than or equal to 1.
Example: 11/4 (eleven-fourths)
You write a mixed number as: Whole Number Numerator/Denominator.
Q: How do I convert a mixed number to an improper fraction?
To convert a mixed number to an improper fraction:
- Multiply the whole number by the denominator of the fraction.
- Add the result to the numerator of the fraction.
- Write this new sum as the numerator of the improper fraction, keeping the original denominator.
Example: Convert 3 ½ to an improper fraction.
- Multiply whole number by denominator:
3 × 2 = 6 - Add the result to the numerator:
6 + 1 = 7 - The improper fraction is
7/2.
This process effectively counts how many "pieces" (defined by the denominator) are in the whole number part and adds them to the pieces in the fractional part.
Q: How do I convert an improper fraction to a mixed number?
To convert an improper fraction to a mixed number:
- Divide the numerator by the denominator.
- The quotient (the whole number part of the division result) becomes the whole number part of the mixed number.
- The remainder of the division becomes the numerator of the fractional part.
- The original denominator stays the same.
Example: Convert 11/4 to a mixed number.
- Divide 11 by 4:
11 ÷ 4 = 2with a remainder of3. - The quotient (whole number) is
2. - The remainder (new numerator) is
3. - The denominator stays
4. - The mixed number is
2 ¾.
Q: How do I multiply mixed numbers (with fractions, whole numbers, or other mixed numbers)?
The easiest way to multiply mixed numbers is to first convert them into improper fractions.
- Convert all mixed numbers (and whole numbers) to improper fractions.
- To convert a mixed number, see the FAQ above.
- To convert a whole number to an improper fraction, write the whole number over 1 (e.g.,
5becomes5/1). - Regular fractions are already in the correct format.
- Multiply the numerators together to get the new numerator.
- Multiply the denominators together to get the new denominator.
- Simplify the resulting fraction if possible, and convert it back to a mixed number if it's improper and the context requires it.
Example 1: Multiply 1 ½ by 2 ¾
- Convert to improper fractions:
1 ½ = 3/2and2 ¾ = 11/4. - Multiply numerators:
3 × 11 = 33. - Multiply denominators:
2 × 4 = 8. - Result:
33/8. - Convert back to mixed number:
33 ÷ 8 = 4with a remainder of1. So,33/8 = 4 ⅛.
Example 2: Multiply 2 ⅓ by ⅖ (mixed number by a fraction)
- Convert
2 ⅓to7/3. The fraction⅖stays as is. - Multiply numerators:
7 × 2 = 14. - Multiply denominators:
3 × 5 = 15. - Result:
14/15(already a proper fraction).
Example 3: Multiply 1 ¼ by 3 (mixed number by a whole number)
- Convert
1 ¼to5/4. Convert3to3/1. - Multiply numerators:
5 × 3 = 15. - Multiply denominators:
4 × 1 = 4. - Result:
15/4. Convert to mixed number:3 ¾.
Q: How do I divide mixed numbers (with fractions, whole numbers, or other mixed numbers)?
Similar to multiplication, first convert all mixed numbers (and whole numbers) to improper fractions.
- Convert all mixed numbers (and whole numbers) to improper fractions. (See multiplication FAQ for conversion details).
- Keep the first fraction as it is.
- Change the division sign to a multiplication sign.
- Flip (invert) the second fraction (the divisor). This is called finding the reciprocal.
- Multiply the fractions as described in the multiplication FAQ (multiply numerators, multiply denominators).
- Simplify the result and convert to a mixed number if needed.
Example: Divide 3 ½ by 1 ¾
- Convert to improper fractions:
3 ½ = 7/2and1 ¾ = 7/4. - The problem becomes
7/2 ÷ 7/4. - Keep the first, change to multiply, flip the second:
7/2 × 4/7. - Multiply numerators:
7 × 4 = 28. - Multiply denominators:
2 × 7 = 14. - Result:
28/14. - Simplify:
28/14 = 2.
This process applies when dividing a mixed number by a fraction, a mixed number by a whole number, or a whole number by a mixed number – always convert to improper fractions first.
Q: How do I add mixed numbers?
There are two common methods for adding mixed numbers:
Method 1: Add Whole Numbers and Fractions Separately
- Add the whole number parts together.
- Add the fractional parts together.
- If the fractions have different denominators, find a common denominator first.
- If the sum of the fractions is an improper fraction, convert it to a mixed number and add its whole number part to the sum of the whole numbers.
- Combine the results and simplify the final fractional part if needed.
Example: Add 2 ¼ + 1 ½
- Add whole numbers:
2 + 1 = 3. - Add fractions:
¼ + ½. Find common denominator (4):¼ + 2/4 = ¾. - Combine:
3 ¾.
Method 2: Convert to Improper Fractions
- Convert all mixed numbers to improper fractions.
- Find a common denominator if the denominators are different.
- Add the numerators, keeping the common denominator.
- Convert the resulting improper fraction back to a mixed number and simplify.
Example: Add 2 ¼ + 1 ½ using improper fractions
- Convert:
2 ¼ = 9/4,1 ½ = 3/2. - Common denominator for
9/4and3/2(which is6/4) is 4. - Add:
9/4 + 6/4 = 15/4. - Convert back:
15/4 = 3 ¾.
This applies to adding mixed numbers with fractions (treat the fraction as having a whole part of 0) or with whole numbers (treat the whole number as having a fractional part of 0).
Q: How do I subtract mixed numbers?
Similar to addition, there are two main methods:
Method 1: Subtract Whole Numbers and Fractions Separately (with potential borrowing)
- Subtract the fractional parts.
- Find a common denominator if necessary.
- If the first fraction is smaller than the second, you'll need to "borrow" 1 from the whole number part of the first mixed number. Add this borrowed 1 (in the form of fraction, e.g.,
4/4,5/5) to the first fraction before subtracting.
- Subtract the whole number parts.
- Combine the results and simplify.
Example: Subtract 3 ¼ – 1 ¾
- Fractions:
¼ – ¾. Since¼is smaller than¾, borrow 1 from the3. The3becomes2. The borrowed1is added to¼as4/4, so¼ + 4/4 = 5/4. Now subtract fractions:5/4 – ¾ = 2/4. - Whole numbers:
2 – 1 = 1(remember we borrowed from the 3). - Combine:
1 2/4. Simplify:1 ½.
Method 2: Convert to Improper Fractions
- Convert all mixed numbers to improper fractions.
- Find a common denominator if necessary.
- Subtract the numerators, keeping the common denominator.
- Convert the result back to a mixed number and simplify if needed.
Example: Subtract 3 ¼ – 1 ¾ using improper fractions
- Convert:
3 ¼ = 13/4,1 ¾ = 7/4. - Subtract:
13/4 – 7/4 = 6/4. - Convert back and simplify:
6/4 = 1 2/4 = 1 ½.
This applies when subtracting a fraction from a mixed number, or a mixed number from a whole number (convert the whole number to a mixed number with a 0 fraction or to an improper fraction).
Q: How do I convert mixed numbers to decimals?
To convert a mixed number to a decimal:
- Keep the whole number part as it is; this will be the part of the decimal before the decimal point.
- Convert the fractional part to a decimal by dividing the numerator by the denominator.
- Combine the whole number part and the decimal part.
Example: Convert 3 ¾ to a decimal.
- The whole number part is
3. - Convert the fraction
¾: Divide3by4.3 ÷ 4 = 0.75. - Combine: The whole number
3plus the decimal0.75gives3.75.
Alternatively, convert the mixed number to an improper fraction first, then divide the numerator by the denominator. For 3 ¾ = 15/4, then 15 ÷ 4 = 3.75.
Q: How do I convert decimals to mixed numbers?
To convert a decimal to a mixed number (if the decimal is greater than 1):
- The whole number part of the decimal becomes the whole number part of the mixed number.
- Take the decimal part (the digits after the decimal point) and write it as the numerator of a fraction.
- The denominator of the fraction will be a power of 10 (10, 100, 1000, etc.) corresponding to the number of decimal places.
- 1 decimal place: denominator is 10.
- 2 decimal places: denominator is 100.
- 3 decimal places: denominator is 1000, and so on.
- Simplify the fractional part of the mixed number to its lowest terms.
Example: Convert 5.25 to a mixed number.
- The whole number part is
5. - The decimal part is
.25. Write this as25(numerator). - There are two decimal places, so the denominator is
100. The fraction is25/100. - Combine:
5 25/100. - Simplify the fraction
25/100by dividing both numerator and denominator by their greatest common divisor (25):25÷25 / 100÷25 = 1/4. - The mixed number is
5 ¼.
Q: How do I simplify mixed numbers?
To simplify a mixed number, you simplify its fractional part. The whole number part remains unchanged unless the fractional part was improper and got converted, changing the whole number.
- Look at the fractional part of the mixed number.
- Find the greatest common divisor (GCD) of the numerator and the denominator.
- Divide both the numerator and the denominator by their GCD.
Example: Simplify 4 6/8.
- The fractional part is
6/8. - The GCD of 6 and 8 is 2.
- Divide numerator by GCD:
6 ÷ 2 = 3. - Divide denominator by GCD:
8 ÷ 2 = 4. - The simplified fractional part is
¾. - The simplified mixed number is
4 ¾.
If an operation results in a mixed number with an improper fraction (e.g., 2 5/3), first convert the improper fraction part to a mixed number (5/3 = 1 2/3), then add the whole parts (2 + 1 2/3 = 3 2/3).
