What is the highest digit that can be used in each place value?

In the decimal number system, the highest valued digit is 9.

The highest digit that ever appears in any one 'place' of a number is one less than the

'base' of the number.

The numbers that everyone is most familiar with ... the numbers you see around you

every day ... are numbers written in the 'decimal' system, using the 'base' of 10. So

the highest digit in any one place is 9.

'Binary' numbers ... the form most used to represent numbers inside digital circuits and computers ...

are constructed in base 2. So the highest digit in any one place is 1, and each

of these numbers is just a string of 1's and zeros.

Digits can be even higher than 9 in number systems that use other bases. For example, the hexadecimal system (often used in computer science to represent binary numbers) is base 16, so in that case the highest valued digit is "F" which has a value equivalent to 15 in a decimal representation. As an example, the number "FA" hexadecimal, has decimal value 15*16 + 10 = 250.