There are 3 terms which we have been using, which can be confusing in their meaning. These are digit, numeral & number. We will clarify their meanings.
Digit
Digit is the shape with which a number less than ten is represented/ written.
In Hindu Arabic numbers, the digits are 0, 1, 2, 3, 4, 5, 6, 7, 8 and 9.
१, २, ३ …… are the digits in Hindi language.
Each language may have its own digits.
The digits in the Roman Number system are I, V, X, C, L , M etc
The word literally means "part of a finger." It shows the deep mental connection that humans made between counting (with fingers) and math.
Numeral
Numeral is a string of digits, which could be interpreted in different ways.
2021 & 3.5 are numerals if we are not sure of their interpretation.
2021 could be the “chest number” of a runner in a marathon.
3.5 could be the number of overs & balls bowled.
Number
Number is a measure of a quantity. It is an idea.
A digit or a numeral is interpreted as a number depending on the “code” which has been agreed on for interpretation.
The most common code for interpreting numerals is the decimal place value system.
2021 can mean different quantities depending upon the base of the place value system used to interpret it.
In base ten, it is interpreted as Two Thousand and Twenty One.
In base 8, its interpretation could be as a different value