Positive numbers are greater than zero, negative numbers are less than zero. Opposite numbers are the same distance from zero but in opposite directions. Integers include all whole numbers and their opposites on a number line. When adding positive and negative numbers, if the signs are the same you add the numbers and keep the sign, if the signs are different you subtract the smaller number and use the sign of the larger number. Adding numbers on a number line involves counting right for positive numbers and left for negative numbers.