Multiplying a Fraction by a Whole Number
Aligned to 4.NF.B.4 — Common Core State Standards for Mathematics.
What this lesson teaches
Multiplying a whole number by a fraction means adding that fraction that many times. Multiply the whole number by the numerator and keep the denominator the same. If the answer is bigger than one, you can write it as a mixed number.
Worked examples
Example 1
3 x 2/5. This means 2/5 + 2/5 + 2/5. Multiply the whole number by the numerator: 3 x 2 = 6, keep the denominator 5. Answer: 6/5. Since 5/5 makes one whole, 6/5 = 1 and 1/5.
Example 2
4 × 3/8 means 3/8 four times: 4 × 3 = 12, keep the 8. Answer: 12/8, which is 1 and 4/8.
Example 3
A recipe calls for 2/3 cup of flour and you triple it: 3 × 2/3 = 6/3 = 2 whole cups.
Practice questions
- Find 4 x 1/3.
- Find 5 x 2/6.
- A recipe uses 3/4 cup of flour. How much flour for 3 batches? Write it as a mixed number.
Watch the lesson
Every lesson comes with a video taught in English and Spanish — the same video the QR code in the printed workbook opens.
▶ Watch this lessonEn español
Multiplicar una fracción por un número entero
Multiplicar un número entero por una fracción significa sumar esa fracción esa cantidad de veces. Multiplica el número entero por el numerador y deja el denominador igual. Si el resultado es mayor que uno, puedes escribirlo como número mixto.
Ejemplo 1: 3 x 2/5. Esto significa 2/5 + 2/5 + 2/5. Multiplica el entero por el numerador: 3 x 2 = 6 y deja el denominador 5. Respuesta: 6/5. Como 5/5 forma un entero, 6/5 = 1 y 1/5.
Ejemplo 2: 4 × 3/8 significa 3/8 cuatro veces: 4 × 3 = 12 y deja el 8. Respuesta: 12/8, que es 1 y 4/8.
Ejemplo 3: Una receta pide 2/3 de taza de harina y la triplicas: 3 × 2/3 = 6/3 = 2 tazas enteras.
More Number & Operations—Fractions lessons
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