Question

how many 4 digit numbers will not exceed 7432 if they are formed using the digits 2, 3, 4,7 someone without repetition.....​

Answer 1

Hello Mate,

Here is your answer,

Digits Given: 2, 3, 4, 7

Number that should not be exceeded

= 7432

Here the number 7432 can be the only largest valued number formed with the given digits as all digits are placed in the descending order.

So all the other numbers excluding 7432

can be formed.

So the no. of numbers that can be formed are:

4! - 1

(We are subtracting '1' as 7432 is not included.)

4! = 24

24 - 1

= 23

So 23 no. of numbers can be formed, that are smaller than 7432, with it as excluded.

Hope you understood the logic behind this.. :)

Hope it helps:)

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Answer 2

Total 4 digit numbers will not exceed 7432 = 24 - 1 = 23

Step-by-step explanation:

We have 4 options for the first digit

We have 3 options for the second digit.

We have 2 options for the 3rd digit.

We have only 1 option for the fourth digit.

The total number of four digits numbers formed = 4 × 3 × 2 × 1

= 24

Total 4 digit numbers will not exceed 7432 = 24 - 1 = 23

Hence, 23 numbers can be formed.