0 votes 0 votes closed as a duplicate of: MadeEasy Subject Test 2019: Combinatory - Permutations And Combinations The number of ways, we can arrange 5 books in 3 shelves ________. Given answer 2520 n=3 r=5 so answer is 3-1+5 P5= 7p5= 2520 My answer 3*3*3*3*3= 243 Where am I doing wrong? please help Combinatory combinatory + – Mayank Bansal asked Jan 29, 2019 • closed Jan 29, 2019 by Mk Utkarsh Mayank Bansal 251 views comment Share Follow See all 2 Comments See all 2 2 Comments reply OneZero commented Jan 29, 2019 reply Follow Share https://gateoverflow.in/300636/madeeasy 1 votes 1 votes Mayank Bansal commented Jan 30, 2019 reply Follow Share Thanks 0 votes 0 votes Please log in or register to add a comment.