CAT 2018 Slot 1 QA Q14 Permutations & Probability

Question 14 of the Quantitative Ability (QA) section, CAT 2018 Slot 1, with CAT's official answer.

How many numbers with two or more digits can be formed with the digits 1, 2, 3, 4, 5, 6, 7, 8, and 9 so that in every such number, each digit is used at most once and the digits appear in the ascending order?[TITA]

TITA: type in the answer. There are no options and no negative marking.

Answer: 502 Permutations & Probability TITA

A worked solution for this question is being written. Meanwhile, practise it in a timed mock and see how other aspirants did.