How do you add fractions with different denominators?
Respuesta corta
Make the denominators the same first. Find a common denominator (the lowest common multiple is easiest), change each fraction to an equivalent fraction with that denominator, then add the numerators and keep the denominator. For example, 1/3 + 1/4 = 4/12 + 3/12 = 7/12.
Paso a paso
- Look at the two denominators and find the smallest number both divide into.
- Change each fraction: whatever you multiply the bottom by, multiply the top by the same number.
- Add the numerators. The denominator stays the same.
- Simplify the answer if you can, and change top-heavy fractions to mixed numbers if asked.
Ejemplo resuelto
Work out 2/5 + 3/10
- 10 is a multiple of 5, so use 10 as the denominator
- 2/5 = 4/10
- 4/10 + 3/10 = 7/10
Errores comunes
- Adding the denominators: 1/3 + 1/4 is not 2/7.
- Changing the denominator without changing the numerator.
- Forgetting to simplify, for example leaving 6/8 instead of 3/4.
Útil para:KS2 SATsCommon EntranceCPE
Una clase particular es la forma más rápida de reforzar lo que te falta antes de un examen. La primera clase es gratis.
Encontrar un profesor de Matemáticas