There are 9000 4-digit numbers. 8*9*9*9 = 5832 of them do not contain a 5 The remaining 3168 contain a 5.
-5
There is a possible confusion over how the last part of your question ("contain no 5") can be interpreted:it could be a badly written shorthand of the word number: "Nº" also written "No." also written "No" and very badly written as "no", meaning "contains the number 5", meaning "the number 5" - the number between 4 and 6 and less than 10;it could be a badly written shorthand of the word number: "Nº" also written "No." also written "No" and very badly written as "no", meaning "contains the number 5", meaning "the digit 5" - the digit 5 in any place value column;It negates the sense so that "contain no 5" means "do not contain the digit 5".In interpretation number 1 there are no such numbers, as 5 is less than 10 and all two digit numbers are greater than, or equal to 10 (I suspect that this meaning is definitely not intended).There are 90 two digit numbers (10 - 99); of them:9 contain a 5 as the second digit: 15, 25, ..., 9510 contain a 5 as the first digit: 50, 51, ..., 59So there are 19 of the digit 5 used.However, 55 is counted twice, meaning there are 18 numbers which contain the digit 5. (This is the solution to the interpretation number 2.)Which means there are 90 - 18 = 72 numbers which do not contain the digit 5. (The solution to interpretation number 3, which I suspect is the required answer.)Use whichever solution meets your intended interpretation of the question you wrote.
-5
17
There are 9000 4-digit numbers. 8*9*9*9 = 5832 of them do not contain a 5 The remaining 3168 contain a 5.
-5
There are 6804 such numbers.
271 of the first 1000 natural numbers contain at least one digit 5. That is 27.1 % of them.
There is a possible confusion over how the last part of your question ("contain no 5") can be interpreted:it could be a badly written shorthand of the word number: "Nº" also written "No." also written "No" and very badly written as "no", meaning "contains the number 5", meaning "the number 5" - the number between 4 and 6 and less than 10;it could be a badly written shorthand of the word number: "Nº" also written "No." also written "No" and very badly written as "no", meaning "contains the number 5", meaning "the digit 5" - the digit 5 in any place value column;It negates the sense so that "contain no 5" means "do not contain the digit 5".In interpretation number 1 there are no such numbers, as 5 is less than 10 and all two digit numbers are greater than, or equal to 10 (I suspect that this meaning is definitely not intended).There are 90 two digit numbers (10 - 99); of them:9 contain a 5 as the second digit: 15, 25, ..., 9510 contain a 5 as the first digit: 50, 51, ..., 59So there are 19 of the digit 5 used.However, 55 is counted twice, meaning there are 18 numbers which contain the digit 5. (This is the solution to the interpretation number 2.)Which means there are 90 - 18 = 72 numbers which do not contain the digit 5. (The solution to interpretation number 3, which I suspect is the required answer.)Use whichever solution meets your intended interpretation of the question you wrote.
19
-5
17
It would help to know which digit. 0 appears in 9 numbers and each of the others in 18 numbers.
1
-2
Six three-digit numbers contain only the digits 5 and 6. This is assuming you mean both the digits of 5 and 6. If not than 8, as it would include 555 and 666. 556, 565, 566, 655, 656, 665