Addition is the mathematical process of putting things together, that is to say joining. With the addition of two numbers, the process may be thought of moving a certain distance in the positive direction. If one considers the following equation:
The plus sign or addition symbol ( + ) marks that addition is preformed on its adjacent numerals (a and b). C is called the sum of a and b. This equation may be calculated by moving a, b whole units in the positive direction.
Taking in account the analogy from the previous section,
may be thought of as moving 3 in the positive direction by 4 units:
with may be counted to achieve the answer of 7.
Addition sums are possible to be estimated. It is done by rounding off each addend to the nearest n significant figures (where n is a whole number), and adding both of the rounded numbers.