Write the immediate successor and predecessor of the following numbers.

$12345$

Write the immediate successor and predecessor of the following numbers.

$78989$

Write the immediate successor and predecessor of the following numbers.

$24780$

Write the immediate successor and predecessor of the following numbers.

$17900$

What is the smallest whole number? (Mention the answer in figures)

What is the smallest natural number? Write the answer in numeral.

The successor of a greatest $2$-digit number is always a _____ digit number. Write the answer in words.

The immediate successor of the smallest $3$-digit number is a _____

The immediate predecessor of the smallest $3$-digit number is _____ digit number. Write the answer in words.