In performing computations with real numbers, it is important to remember the rules
for computations.
1. (a) To add two real numbers with the same sign,
add their absolute values and affix their common
sign.
(b) To add two real numbers with unlike signs, find
the difference of their absolute values and affix
the sign of the number with the larger absolute
value.
2. To subtract one real number from another, change
the sign of the number being subtracted and proceed
as in addition.
3. (a) The product of two real numbers with like signs
is positive.
(b) The product of two real numbers with unlike
signs is negative.
4. (a) The quotient of two real numbers with like signs
is positive.
(b) The quotient of two real numbers with unlike
signs is negative.
When two or more operations with real numbers are indicated in an evaluation, it is
important that everyone agree on the order in which the operations are performed so that
a unique result is guaranteed. The following order of operations is universally accepted.