Answer: The predecessor of 10000 is 9999. Predecessor means a number immediately before the given number. To find the predecessor of a number, subtract 1 from the number. Therefore we will subtract 1 from 10000. 10000-1= 9999. Hence 9999 is the answer.
Similarly, we can find the successor of a number by adding 1 to the given number because successor means the immediate next number.