What Have We Discussed ?

1.We have seen that there are times when we need to use numbers with a negativepositive sign.

This is when we want to go below on the number line. These are called numbers.

Some examples of their use can be in temperature scale, water level in lake or river, level of oil in tank etc.

They are also used to denote debit account or outstanding dues.

The collection of numbers..., – 4, – 3, – 2, – 1, 0, 1, 2, 3, 4, ... is called .

So, – 1, – 2, – 3, – 4, ... called numbers are negative integerspositive integers and 1, 2, 3, 4,... called numbers are thepositive integersnegative integers.

We have also seen how one more than given number gives a and one less than given number gives .

We observe that:

(a) When we have the same sign, add and put the sign.

(b) When two positive integers are added, we get a positivenegative integer

(c) When two negative integers are added, we get a negativepositive integer

(d) When one positive and one negative integers are added we subtract them as whole numbersintegers by considering the numbers without their sign and then put the sign of the biggersmaller number with the subtraction obtained.

The biggersmaller integer is decided by ignoring the signs of the integers.

(e) The subtraction of an integer is the same as the addition of its inverse.