Addition of integers

Addition of integers

When a positive integer is added to another positive integer, the answer is a positive integer. If a positive integer is added to a negative integer which is smaller in magnitude than that of a positive integer, the answer is positive. Likewise, if a positive integer is added to a negative integer which is larger in magnitude than that of a positive integer, the answer is negative.

Example 1

$+3 + (-2) =$

Solution

Write three positive signs to show a profit of three items. Also, write two negative (minus) signs below the positive signs to show a debt of two items of the same type.

Pay the debt by using the two profit items.

A profit of one item will remain after paying the debt.

Therefore, $+3 + (-2) = +1$

Example 2

$-5 + (-4) =$

Solution

Write five negative (minus) signs to show a debt of five items. Also, write four negative signs below to show another debt of four items of the same type.

The total debt will be 9 items.

Therefore, $-5 + (-4) = -9$