If $432P1$ is completely divisible by $9$,then what is the value of $P$?

If the digit in the unit's place of a two-digit number is halved and the digit in the ten's place is doubled,the number thus obtained is equal to the number obtained by interchanging the digits. Which of the following is definitely true?

What least number should be subtracted from $3401$ so that the result is completely divisible by $11$?

What least number must be added to $1056$ so that the sum is completely divisible by $23$?

Let $x$ be the smallest number,which when added to $2000$ makes the resulting number divisible by $12, 16, 18$ and $21$. The sum of the digits of $x$ is

If the number $583x437$ is completely divisible by $9$,then the smallest whole number in the place of the blank digit $x$ will be