A real number that can NOT be made by dividing two integers (an integer has no fractional part). "Irrational" means "no ratio", so it isn't a rational number. ... Example: π (the famous number "pi") is an irrational number, as it can not be made by dividing two integers.

 are rational numbers. Any fraction can be expressed as a decimal number that either terminates(ends) or repeats (the same all the time). 

 is used to make working with very large or very small numbers easier.  You use a power of ten and numbers are only ones and parts (decimal numbers).

 A number that can be made by dividing two integers (an integer is a number with no fractional part). The word comes from "ratio". Examples: • 1/2 is a rational number (1 divided by 2, or the ratio of 1 to 2) • 0.75 = (3/4)

 are rational numbers since any whole number can be expressed as a fraction (e.g., 5 = 5/1).

 (whole numbers and their opposites) are rational numbers since any integer can be expressed as a fraction (e.g., −4 =  - 4/1 and +8 =  8/1).

The type of number we normally use, such as 1, 15.82, −0.1, 3/4, etc. Positive or negative, large or small, whole numbers or decimal numbers, or irrational numbers.