A "three-digit" number is any whole number that consists of three digits, ranging from 100 to 999. Each digit in a three-digit number represents a different place value: the hundreds, the tens, and the units. For example, in the number 345, the digit 3 is in the hundreds place, 4 is in the tens place, and 5 is in the units place. Three-digit numbers are commonly used in various contexts, such as in mathematics, statistics, and everyday life. They can represent quantities, measurements, or codes, like postal codes or area codes. Understanding three-digit numbers is essential for basic arithmetic and numerical literacy.