Ternary numeral system
A ternary /ˈtɜːrnəri/ numeral system (also called base 3) has three as its base. This means that you can only count with 0, 1, and 2. The first ten numbers (from 0 to 9) in ternary are 00, 01, 02, 10, 11, 12, 20, 21, 22, 100. When all the digits in the number reach 2, you add a 1 in front and change everything else to 0. There is another system with the same name more specifically called the balanced ternary system. This system is called that way because 0 is the middle digit, with the other two digits being -1 and 1. That system is used in comparison logic and ternary computers.