Question

Principle of counting

How many 3 digit numbers can be formed from the four digits 0,1,2,3 if a) no two digits are to be there same? b) the numbers are odd? c) the numbers are even? d) repetition of digits is allowed.

Answer 1

I remember doing a question like this, you need to remember that 0 at the start of a number doesn't count

Answer 2

Spykez is right. It depends what you define as a 3 digit number.
0## is a two digit number, as far as I'm concerned, however some may think otherwise.

Answer 3

lets just operate under that assumption then. that the first digit cant be 0.

Answer 4

3*3*2

Answer 5

b) for numbers are odd u start fill in from back u wanna make sure last digits are either 3 or 1
2*2*2

Answer 6

c)same thing except two cases
one when we use 0 at last, first and one where we dont

Answer 7

1*3*2 +1*2*2

Answer 8

d) 3*4*4

Answer 9

i think this is it

Answer 10

sm1 correct me if i am wrong

Answer 11

can u explain ur answer.. yup u r correct..

Answer 12

which one?

Answer 13

all of it.

Answer 14

LOL sorry ok here goes

Answer 15

wait there's two ways to explain this tree diagram or blank filling in logic which are u more comfortable with

Answer 16

like which one would help u understand better

Answer 17

WOO BIN U THERE?

Answer 18

i got ditched

Answer 19

umm..i think the first question...:))

Answer 20

ok come back in 5 minutes ill upload an attachment that'll help

Answer 21

ok...ty...

Answer 22

ok take a look at this for the first one

Answer 23

Woo bin do u understand?

Answer 24

do u want explanation for the rest as well

Answer 25

i dont mind

Answer 26

but if u dont reply i might go to sleep

Answer 27

ooopss. sorry i was outside the house a moment ago.. it will be cool if u do give an explanation of the other 3 question.. thank you...

Answer 28

ok

Answer 29

#2

Answer 30

man u should be paying me for this awesome explanation

Answer 31

let me do d first
for d its like 1st one except u can do repetition so use all possible digits for 1st one (3,2,1)-->3 , use all for second one (3,2,1,0), use all for third one (3,2,1,0)

Answer 32

hence 3 X 4 X 4

Answer 33

and C there are two cases one where we utilise 0 as last digit and one where we dont
if we do then
1*3*2
where one is the third blank where we put 0
where 3 is the first blank cause we can use (3,2,1)
where 2 is second blacnk cause we can only use either (2,1) or (3,1) or (3,2) depending on what we chose before in third blank

Answer 34

if we chose to utilise 2 as even last digit
if we do then
1*2*2
where 1 is the third blank where we put 2
where 2 is the first blank cause we can use (1,3,) 0 cant be used
where 2 is second blacnk cause we can only use either (0,1) or (3,1) or (3,0) depending on what we chose before in third blank

Answer 35

cool thank u very much!

Answer 36

add the two cases up

Answer 37

np, cause of u im prob late for tennis

Answer 38

dont take it to heart though

Answer 39

bye

Answer 40

ha4....soryy for that i wish u luck...

Answer 41

i like ur dp though

Answer 42

uchiha all the way

Answer 43

yeah..thank you... for u time..:))