Question

I need help with this question it is of permutation
How many three digits number can be formed with each digit being distinct help ?

Answer 1

@shamim The question is how many 3 digit numbers can be formed in which there is no repetition of any number that is each digit is different ?
for example 678 how many such numbers can be made with 10 natural numbers

Answer 2

@ipm1988 Do you have answer choices?

Answer 3

no @uri

Answer 4

9P3=9*8*7

Btw @shamim How do we get 9? :)

Answer 5

@shamim would it not be 7*9*10 @uri

Answer 6

@shamim Waat.

Answer 7

@ash2326

Answer 8

There are ten digits 0-9
Now hundredth place can't be 0, it'll make the no. a 2 digit
So we have 9 choices for the the 100th place. Do you get this @ipm1988

Answer 9

@uri _ _ _ these three blanks represent the numbers so if we take natural number then units can be filled in 10 ways that is 0 to 9 , tens can be filled in 9 ways and hundreds can be filled in 7 ways so it should be 7*9*10

Answer 10

@ash2326 @uri @shamim

Answer 11

@ash2326 but when you generally fill up numbers you start from right that is from units placce

Answer 12

it doesn't matter, we can work both ways

Answer 13

so answer should be 630 @ash2326

Answer 14

Do you have the answer given?

Answer 15

@ipm1988 You're in which grade?

Answer 16

yes the answer 648 = 9*9*8 that is what is confsuing me @uri @shamim @ash2326

Answer 17

If we work from the units place,
first place can be filled in 10 ways, second can be in 9. But how do you have 7 for the hundredth?
It's not that simple you have to consider cases where 0 is not being used, and where you have 0 being used.

Answer 18

@uri I am in first year college just brushing up on some concepts

Answer 19

@ipm1988 Are you ok with the last post I made?

Answer 20

@ash please explain

Answer 21

@ash2326 please explain I mean I get this you can either use whole or natural numbers zero i also understand but explain

Answer 22

ok. Suppose we don't use 0, we have 9 no.s at hand
_ _ _

unit's place- 9
ten's- 8
hundred's- 7
Total distinct no.s - 9 x 8 x 7=504

Answer 23

That means i was right..and @shamim too

Answer 24

9P3=9*8*7=504

Answer 25

Uri we have to also consider the cases where 0 is being used, so the answer would be larger than this

Answer 26

@ipm1988 do you get my last post?

Answer 27

10p3

Answer 28

@ash2326 yes thanks