Question

Mention the predecessor and successor of the number $21$.

Answer 1

Predecessor and Successor of a number.

A whole number that comes just before the given number is recognized as the predecessor of the given number. It is $1$ less than the given number.

A whole number that comes just after the given number is recognized as the successor of the given number. It is $1$ more than the given number.

Therefore,

The predecessor of $21$ is $21-1=20$.

The successor of $21$ is $21+1=22$.

Hence, the predecessor and successor of the number $21$ are $20$ and $22$ respectively.