When you are writing an integer, there are two parts in the written expression the sign and the absolute value. Integer sets are both infinite both in the negative and the positive directions, therefore - (20) can be written using a number line where on the negative side you put dot or a mark to indicate is a negative number.
2 years ago
Last edited at 5:48PM on 8/31/2011
An integer is any whole number (no decimal or fraction) including 0 and includes negative and positive numbers. Don't quite know what u mean "an expresson for" but you can write an expression for all integers with a number line with dots above each whole number to infinity in both directions