Permutations and Combinations!

how many 5 digit numbers can be formed that do not contain the digits 0 or 8?

9*9*8*7*6 = 27,216

Step-by-step explanation:

Your answer is : - 9*9*8*7*6 = 27,216

Why did i multiply 9*9*8*7*6 ⤵️

Because we can fill each place of a five digit number with ten digits (0,1,2,3,4,5,6,7,8,9).

Now, let us assume the five digit number is abcde, where each alphabet represent a digit.

so according to our question a cannot be equal to 0 (a≠0), because if a will be equal to zero then our number will be a four digit number. So a can be equal to 9 digits.

b digit can also be equal to 9 numbers. why? because we can place zero on the position of b and only one number will not be repeated which is a.

Now for c, d, e : - accordingly no number will be repeated so on the place of c, there can be 8 digits. On the place of d, there can be 7 digits. And on the place of e there can be 6 digits.

Therefore,

a*b*c*d*e=9*9*8*7*6=27,216