Número vs. cifra
While both número and cifra can be translated as number in English, they are not interchangeable in Spanish. Número refers to the abstract concept or value of a number, while cifra refers to the individual symbols that represent a number or to a statistical figure.
Número
A1Número is the general and most common word for number. It refers to the entire mathematical value, a quantity, or an identifying code (like a phone or house number). It represents the idea of the number itself.
Mi número favorito es el siete.
(My favorite number is seven.)
Por favor, anote mi número de teléfono.
(Please, write down my phone number.)
El número de participantes en el evento fue muy alto.
(The number of participants in the event was very high.)
¿Cuál es el número de la página?
(What is the page number?)
Treinta es un número par.
(Thirty is an even number.)
Necesitamos un número mayor de voluntarios.
(We need a greater number of volunteers.)
Cifra
B1Cifra has two distinct meanings. It can mean digit—one of the symbols from 0 to 9 used to write a number. It is also very commonly used to mean figure in a statistical context, referring to a quantity or amount, especially a large or official one.
El número 482 tiene tres cifras.
(The number 482 has three digits.)
Mi contraseña es un código de seis cifras.
(My password is a six-digit code.)
La última cifra de la lotería fue el 9.
(The last digit of the lottery was 9.)
Las cifras de ventas de este año son impresionantes.
(This year's sales figures are impressive.)
El gobierno publicó la cifra oficial de desempleo.
(The government published the official unemployment figure.)
La donación alcanzó una cifra récord.
(The donation reached a record figure.)
Summary
In essence, use número for the concept of a number, a quantity, or an identifier. Use cifra when referring to the individual digits (0-9) that make up a number, or when discussing statistical amounts, often translated as figures in English. A número is composed of one or more cifras.