How do you terminate decimals?

Answer 1

You do not terminate decimals. Either they do or they don't but it is the number that decides.

If the number, is rational and in its lowest form, the only prime factors of the denominator are 2 or 5 then the decimal will terminate. If the number is rational but in its simplest form the denominator has any other factor, it will have a recurring decimal representation. If it is irrational, then it will have an infinite, non-recurring decimal representation.

You can choose to truncate or round a decimal: either after a selected number of decimal digits or significant figures.

• To truncate, you simply go as far as you wish and ignore all the subsequent digits.
• To round, you go as far as you wish and then if what follows is
  • less than 5 then you truncate,
  • greater than 5 then you increase the final digit by one, and
  • equal to 5 you truncate or round up so that the final digit is even.

For rounding when what follows is 5, many schools instruct pupils to round up, but that is wrong since it introduces an upward bias. The round-to-even rule conforms with the IEEE standard (754).