I was thinking recently about these two words.

Problem:
Some people use these two nouns interchangeably, but they are not synonyms.

Explanation:
As noted at Wikipedia, “A number is an abstract object, tokens of which are symbols used in counting and measuring.”

In contrast, a “numeral” is a symbol used to represent a number.

There are many different numeral systems. For example, the Roman numeral for five is “V”. The Hindu-Arabic numerals are the ten digits 0, 1, 2, 3, 4, 5, 6, 7, 8, and 9.

Solution:
Use “numeral” to refer to the symbol; use “number” otherwise.