Question

A total of 24 four-digit numbers can be made using all the given digits 1, 2, 3, 4 only once. What is the sum of all these numbers?​

Answer 1

Answer:

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Step-by-step explanation:

You have to form a 4 digit number using the digits 1,2,3,4 with the constraint that the digits cannot be repeated.

Let us say that you have four blank places _ _ _ _ where you will place the digits in order to form a 4 digit number.

For first place, you have 4 options (1,2,3,4) and you can go with any of them.

Once you fill the first place, you are left with 3 options for the second place, since you cannot repeat the digits.

Once you do that too, you have just 2 options to fill the third place.

And finally, you have no option but to fit the only digit left, in the last place.

So, total no. of ways = 4*3*2*1 = 24