Recipe Scaling
A recipe calls for 2 1/4 cups of flour and serves 4 people. Doubling it for 8 people needs 2 1/4 × 2 = 4 1/2 cups.
A finer way to compute
Add, subtract, multiply and divide mixed numbers with jeweler-grade precision. Type a value and watch the result, the working, and the diagram update instantly — no button required.
Type the whole number, numerator, and denominator into their own fields. For a negative value such as −2 3/4, use the sign toggle or type −2 in the whole-number field.
Result
Visual Studio
A live, interactive diagram redraws itself with every value you enter — gold wedges fill in, bars stretch and points glide as your fraction grows.
First value
Second value
Result
Each filled dot is one complete unit and the partly filled dot is the fraction left over. The ring sweep shows how far past the last whole unit the value sits, so 5 3/4 draws five dots and a three-quarter sweep.
Definition
A mixed number is a whole number joined with a proper fraction, such as 2 3/4 or 1 1/2. The whole number counts complete units. The fraction counts a part left over, and its numerator is smaller than its denominator.
An improper fraction differs from a mixed number in one way: its numerator is equal to or larger than its denominator, such as 11/4. A whole number differs too — it has no fraction part at all, such as 5.
Four examples of mixed numbers:
Conversion
The formula multiplies the whole number by the denominator, adds the numerator, and places the result over the same denominator.
Formula
Example — 1 3/4 to an improper fraction
1 3/4 = (1×4 + 3) / 4 = 7/4
Example — 2 3/8 to an improper fraction
2 3/8 = (2×8 + 3) / 8 = (16 + 3) / 8 = 19/8
Negative example — −2 3/8 to an improper fraction
The negative sign carries through the whole conversion: −2 3/8 = −((2×8 + 3) / 8) = −19/8
Conversion
Divide the numerator by the denominator. The quotient becomes the whole number, and the remainder becomes the new numerator over the same denominator.
Formula
Example — 7/4 to a mixed number
7 ÷ 4 = 1 remainder 3, so 7/4 = 1 3/4
Example — 43/12 to a mixed number
43 ÷ 12 = 3 remainder 7, so 43/12 = 3 7/12
Operation
Add mixed numbers by adding the whole numbers and the fractions separately, then simplifying the result.
Adding fractions formula
Add mixed numbers with the same denominator by adding the whole numbers, adding the numerators, and keeping the denominator unchanged.
Add the whole numbers
2 + 3 = 5
Add the numerators
1/8 + 5/8 = 6/8 — the denominator stays at 8
Simplify the fraction
6/8 → 3/4
Combine
5 + 3/4 = 5 3/4
2 1/8 + 3 5/8 = 5 3/4
Add mixed numbers with different denominators by converting both fractions to a shared least common denominator (LCD) first.
Find the LCD
of 3 and 2: multiples of 3 are 3, 6, 9; multiples of 2 are 2, 4, 6; the LCD is 6
Rewrite each fraction over 6
2/3 → 4/6, and 1/2 → 3/6
Add the fractions
4/6 + 3/6 = 7/6 = 1 1/6
Add the whole numbers
4 + 1 = 5, plus the extra whole unit from 7/6, giving 6 1/6
4 2/3 + 1 1/2 = 6 1/6
The improper fraction method converts both mixed numbers first, then applies the adding fractions formula directly.
Convert to improper fractions
1 2/6 → 8/6, and 2 1/4 → 9/4
Apply the formula
8/6 + 9/4 = (8×4 + 9×6) / (6×4) = (32 + 54) / 24 = 86/24
Simplify
86/24 → GCF 2 → 43/12
Convert back to a mixed number
43/12 = 3 7/12
1 2/6 + 2 1/4 = 3 7/12
Operation
Subtract mixed numbers by subtracting the whole numbers and the fractions separately, borrowing from the whole number when the first fraction is smaller than the second.
Subtracting fractions formula
Subtract mixed numbers with the same denominator by subtracting the whole numbers and the numerators separately, then keeping the denominator unchanged.
Subtract the whole numbers
5 − 2 = 3
Subtract the numerators
3/4 − 1/4 = 2/4 — the denominator stays at 4
Simplify the fraction
2/4 → 1/2
Combine
3 + 1/2 = 3 1/2
5 3/4 − 2 1/4 = 3 1/2
Borrowing is required when the first fraction is smaller than the second. Borrow 1 from the whole number and add a full denominator's worth to the fraction before subtracting.
Compare the fractions
1/4 is smaller than 3/4, so borrowing is needed
Borrow 1 from the 6
making it 5, and add 4/4 to 1/4, giving 5/4
Rewrite the problem
as 5 5/4 − 2 3/4
Subtract the whole numbers
5 − 2 = 3
Subtract the fractions
5/4 − 3/4 = 2/4 → 1/2
Combine
3 + 1/2 = 3 1/2
6 1/4 − 2 3/4 = 3 1/2
The improper fraction method converts both mixed numbers first, applies the subtracting fractions formula, then simplifies.
Convert to improper fractions
1 2/6 → 8/6, and 2 1/4 → 9/4
Apply the formula
8/6 − 9/4 = (8×4 − 9×6) / (6×4) = (32 − 54) / 24 = −22/24
Simplify
−22/24 → GCF 2 → −11/12
1 2/6 − 2 1/4 = −11/12 — negative, because the second value is larger than the first
Operation
Multiply mixed numbers by converting both to improper fractions, then multiplying straight across. No common denominator is needed.
Multiplying fractions formula
Convert, multiply the numerators, multiply the denominators, then reduce.
Convert to improper fractions
1 1/2 → 3/2, and 2 1/3 → 7/3
Multiply straight across
3/2 × 7/3 = 21/6
Simplify
21/6 → 7/2
Convert back
7/2 = 3 1/2
1 1/2 × 2 1/3 = 3 1/2
Cross-simplification cancels common factors between a numerator and the opposite denominator before multiplying, so the numbers stay small.
Convert to improper fractions
3 3/5 → 18/5, and 4 1/6 → 25/6
Cross-cancel
18 and 6 share a GCF of 6, reducing to 3 and 1; 25 and 5 share a GCF of 5, reducing to 5 and 1
Multiply the reduced numbers
3 × 5 = 15
3 3/5 × 4 1/6 = 15
The same two-step conversion works whatever the denominators are.
Convert to improper fractions
1 2/6 → 8/6, and 2 1/4 → 9/4
Multiply straight across
8/6 × 9/4 = 72/24
Simplify
72/24 → GCF 24 → 3
1 2/6 × 2 1/4 = 3 — a whole number, since the fraction part reduced away completely
Operation
Divide mixed numbers by converting both to improper fractions, then multiplying the first by the reciprocal of the second.
Dividing fractions formula
Flip the second fraction and the division turns into a multiplication you already know how to do.
Convert to improper fractions
3 1/2 → 7/2, and 1 1/4 → 5/4
Flip the second fraction
5/4 becomes its reciprocal, 4/5
Multiply
7/2 × 4/5 = 28/10
Simplify
28/10 → 14/5
Convert back
14/5 = 2 4/5
3 1/2 ÷ 1 1/4 = 2 4/5
Cancel diagonally after the flip and the multiplication becomes trivial.
Convert to improper fractions
5 1/3 → 16/3, and 2 2/3 → 8/3
Flip and cross-cancel
16/3 × 3/8 — the two 3s cancel, and 16 and 8 share a GCF of 8, reducing to 2 and 1
Multiply the reduced numbers
2 × 1 = 2
5 1/3 ÷ 2 2/3 = 2
One formula covers every division: multiply the outer terms over the inner terms.
Convert to improper fractions
1 2/6 → 8/6, and 2 1/4 → 9/4
Flip and multiply
8/6 × 4/9 = 32/54
Simplify
32/54 → GCF 2 → 16/27
1 2/6 ÷ 2 1/4 = 16/27
Ten frequently searched division problems, solved.
| Problem | Result |
|---|---|
| 2 1/2 ÷ 5 | 1/2 |
| 9 ÷ 1/5 | 45 |
| 25 3/4 ÷ 2 | 12 7/8 |
| 15 3/8 ÷ 2 | 7 11/16 |
| 9 1/4 ÷ 2 | 4 5/8 |
| 3 5/8 ÷ 2 | 1 13/16 |
| 1 1/2 ÷ 1/2 | 3 |
| 1 2/3 ÷ 1/6 | 10 |
| 3 1/3 ÷ 5 | 2/3 |
| half of 15 3/4 | 7 7/8 |
Reduce
Simplify a mixed number by dividing its numerator and denominator by their greatest common factor (GCF) until no common factor remains.
86/24 → GCF 2 → 43/12 = 3 7/12
Conversion
Mixed numbers and decimals represent the same values in two different formats. Converting between them runs in both directions.
Convert a mixed number to a decimal by dividing the numerator by the denominator, then adding the result to the whole number.
| Mixed number | Decimal |
|---|---|
| 1 1/2 | 1.5 |
| 2 3/4 | 2.75 |
| 3 7/12 | 3.583 |
Convert a decimal to a mixed number by writing the digits after the decimal point over the matching power of 10, then simplifying.
| Decimal | Fraction |
|---|---|
| 1.375 | 1 3/8 |
| 0.8 | 4/5 (no whole number part) |
Special cases
Two situations that still follow the same four formulas: negative values, and a whole number paired with a plain fraction.
A negative mixed number carries its sign across the whole value, not just the whole-number part.
Convert to an improper fraction
−2 3/4 = −11/4, since the sign applies to the full amount (2×4 + 3 = 11)
Operate as usual
(−11×2 + 3×4) / (4×2) = −10/8 = −5/4 = −1 1/4
−2 3/4 + 1 1/2 = −1 1/4
A whole number is a mixed number with 0/1 as its fraction part, so it follows the same four formulas when paired with a fraction.
5 + 3/4 = 5 3/4
5 − 3/4 = 4 1/4
3 × 2/4 = 1 1/2
6 ÷ 1/3 = 18
Lookup
44 improper fractions with denominators from 2 to 16, already converted and simplified. Filter by typing any part of a fraction.
Applications
Mixed numbers show up anywhere a measurement runs past a whole unit.
A recipe calls for 2 1/4 cups of flour and serves 4 people. Doubling it for 8 people needs 2 1/4 × 2 = 4 1/2 cups.
A shelf board measures 32 5/8 inches (82.9 cm). Cutting two equal shelves from it means dividing by 2: 32 5/8 ÷ 2 = 16 5/16 inches (41.4 cm) each.
A concrete mix ratio calls for 1 3/4 parts cement to 3 1/2 parts sand. Tripling the batch needs 1 3/4 × 3 = 5 1/4 parts cement.
A liquid medication dose is 1 1/2 teaspoons (7.5 mL) every 8 hours. Three doses in a day total 1 1/2 × 3 = 4 1/2 teaspoons (22.5 mL).
A skirt pattern needs 1 5/8 yards (1.49 m) of fabric per panel. Four panels need 1 5/8 × 4 = 6 1/2 yards (5.94 m).
A small engine fuel mix uses 2 1/2 gallons (9.46 L) of gasoline per 1/2 pint (0.24 L) of oil. Doubling the ratio gives 5 gallons (18.93 L) of gasoline and 1 pint (0.47 L) of oil.
Questions
12 questions not already answered in full above, grouped by topic.
More tools
Turn any mixed number into an improper fraction instantly.
Switch between mixed numbers and decimals in both directions.
Reduce any fraction to its lowest terms using the GCF.
Add two mixed numbers with full step-by-step working.
Subtract mixed numbers, including borrowing cases.
Multiply mixed numbers with cross-simplification shown.
Divide mixed numbers using the reciprocal method.
Find equal fractions at any denominator.
Find the LCD for two or more fractions.
Browse solved mixed number problems by type.
Convert between fractions, mixed numbers, and percents.