A count, measurement or idea of a value.
We write or talk about numbers using numerals such as "5" or "five". We could also hold up 5 fingers, or tap the table 5 times. These are all different ways of referring to the same number.
There are also different types of numbers, such as
• whole numbers {1,2,3,...}
• decimals (like 1.48 or 50.5)
• fractions (like 1/2 or 3/8)
• and more.