There is no single number that is called the “least” in Bingo. Instead, different Bingo organizations have different rules about what numbers are considered to be the “least.”
One common rule is that the least number in a given Bingo game is the number that is called first. This means that the number that is called first in a game of Bingo is the least number.
Another common rule is that the least number in a given Bingo game is the number that is called last. This means that the number that is called last in a game of Bingo is the least number.
It’s important to know these rules so that you can play Bingo correctly and get the best chance of winning.