Question

How many 5 digit numbers can be formed if each one uses all the digits 0,1,2,3,4 without repetition

Answer 1

Hint: The first digit cannot be 0

Answer 2

So 4?

Answer 3

So, it will be like

Answer 4

Why did you put 4 twice?

Answer 5

2

Answer 6

For first digit we have 4 choices.(As it cannot be zero)
And for the second digit also we have 4 choices.(It can be zero but not the Digit that is first digit)
And for third digit we have 3 choices
And for fourth digit we have 2 choices
And for the fifth digit we have 1 choice

Answer 7

So, its 4*4*3*2*1

Answer 8

got it?

Answer 9

Yea kinda. What about this question
how many 5 digit numbers can be formed (using 0-9)

Answer 10

10*10*10*10*10..right?

Answer 11

ITS 9*9*8*7*6

Answer 12

Is it without repitation?

Answer 13

no

Answer 14

Then, ALWAYS REMEMBER THE FIRST DIGIT CANNOT BE ZERO

Answer 15

So, 9*10*10*10*10

Answer 16

got it?