2 votes 2 votes How many strings of 5 ASCII characters contain the character @ atleast once ? [ NOTE : there are 128 ascii characters ] Answer is : 1,321,368,961 Can anyone explain how ? Combinatory discrete-mathematics kenneth-rosen combinatory + – anumita asked May 17, 2017 edited Mar 6, 2019 by Pooja Khatri anumita 356 views answer comment Share Follow See all 0 reply Please log in or register to add a comment.
Best answer 2 votes 2 votes The most simple solution that I can think of is as follows: Total strings possible = 128^5 strings without @ = 127^5 strings with @ character at least one = 128^5 - 127^5 = 1,321,368,961. this gives the answer Ayan Maiti answered May 17, 2017 edited May 17, 2017 by Ayan Maiti Ayan Maiti comment Share Follow See all 0 reply Please log in or register to add a comment.