The set of natural numbers includes the number used for counting. A negative number is located to the left on the number line. A positive number is located to the right on the number line. Signed numbers are either positive or negative. Rational numbers can be written as quotients of two integers, with denominator not 0.
Irrational numbers are nonrational numbers represented by points on the number line.
Real numbers include all numbers that can be represented by points on the number line, or all rational and irrational numbers. The absolute value of a number is the distance between 0 and the number on the number line. The answer to an addition problem is called the sum. The answer to a subtraction problem is called the difference. The result of multiplication is called the product.