The number of 4 -digit integers in the closed interval 2022 , 4482 formed by using the digits 0 , 2 , 3 , 4 …
Solution
Given the number to be formed by using the digits
Now assuming counting integers starting from
Case-I: if zero on place
(i) , now here at unit place number can take place except zero {as }, so possible way.
(ii) , now here at ten's place number can take place and at unit place all number can take place so total possible way
Case-II: If non-zero number on place
i.e , here at hundredth place possibility will be there and at unit and ten's place possibility will be there, so in total possible cases,
Case -III when counting integers starting from
here total possible cases
Case -IV when counting integers starting from
(i) If or on place
i.e., here total possible cases
(ii) If on place
i.e., here total possible cases
So, total possible cases will be numbers
Asked in: JEE Advanced 2022 (Paper 1)