Some examples of uses of negative numbers in everyday life are calculating the price paid for a service or determining the amount of weight lost. Negative numbers are present in all day-to-day activities that use subtraction or that compute a loss of any kind. Using negative numbers in many circumstances is largely a matter of keeping track of what items must be subtracted instead of added.
Negative numbers function just like positive numbers in many ways. They can be put through all basic arithmetic operations and can even be used to find areas and angles in practical geometry.
In situations in which something is spent or reduced, a negative number can often be used. For example, if a boy took $20 from his grandmother, he might use part of it to buy 3 packs of cards, each worth $2.50. The equation can be written as basic subtraction, as in 20 - 3*(2.50) = 20 - 7.50 = 12.50) or as multiplication of a negative number, as in 20 + 3*(-2.50) = 20 + (-7.50) = 12.50.
The use of negative numbers follows a few basic rules. Adding a negative number is the same as subtracting a positive, as in 4 + (-3) = 4 - 3. Subtracting a negative number is the same as adding a positive, as in 5 - (-2) = 5 + 2. Multiplying or dividing an odd quantity of negative numbers produces a negative result. Multiplying or dividing an even quantity of negative signs produces a positive result.