Question

how many 10 digits no. can be firmed by using the no. 5 and 6​

Answer 1

Answer:

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Step-by-step explanation:

Alright, we have 10 digits i.e. 0 to 9

We have to form a 5 digit number using digit 0 to 9 and without repetition.

So lets assume the 5 digit number to be X1 X2 X3 X4 X5

For X1 we have 9 digits (i.e 1 2 3 4 5 6 7 8 9).Yes we exclude 0 as it will make the number 4 digit instead of 5.Suppose we used 1 for X1.

For X2 we have 9 digits (i.e 0 2 3 4 5 6 7 8 9)Excluding the one which we used above but still we have 9 digits to choose as we include 0 which was absent in X1.Suppose we use 0 now.

For X3 we have 8 digits (i.e2 3 4 5 6 7 8 9 ).Suppose we use 2 now.

For X4 we have 7 digits (i.e 3 4 5 6 7 8 9).Suppose we use 3.

And

For X5 we have 6 digits (i.e 4 5 6 7 8 9).

So,

The total number of 5 digit numbers have no digits repeated is 9x9x8x7x6 which is equal to 27216.

You can use whatever digits you wish except 0 for X1. The answer remains the same.

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