counting question

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- anonymous

counting question

- katieb

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- anonymous

##### 1 Attachment

- anonymous

@ASAAD123 can hlp

- IrishBoy123

you have
1AB2
and
1CD5

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## More answers

- IrishBoy123

A,B,C,D are all somewhere in 0,...9

- IrishBoy123

can you take it from there?

- IrishBoy123

can't give answers!

- anonymous

|dw:1441103308403:dw|

- anonymous

can i solve it by scientific calc

- IrishBoy123

how many ways to choose A, then for each A you choose, how many ways to pick B
repeat for C,D

- anonymous

by npr or ncr

- IrishBoy123

you can do it in your head if you know how to do it

- IrishBoy123

nCr

- anonymous

NO @Nourage

- IrishBoy123

but really, it's easier than that

- anonymous

how i do it by ncr

- IrishBoy123

you have 10 ways to choose A, right?

- anonymous

|dw:1441103482580:dw|

- IrishBoy123

\[C_{1}^{10}\]!!

- IrishBoy123

ie you don't need it

- IrishBoy123

then once you have chosen A, you have 10 ways to choose B

- IrishBoy123

@ASAAD123 's drawing is a really nice clue

- anonymous

i want to do it by calc how

- anonymous

can u tell me

- anonymous

you don't need a calc, you need think about the problem.

- anonymous

i can solve it by think but i want to know how to do it by calc

- anonymous

bec think take alot of time

- anonymous

can u hlp

- anonymous

by calc ncr or npr and how

- anonymous

for the first digit, you have 1 way (1), for second and third digit you have 10 ways(0-9), and for last digit you have 2 ways (2 or 5). then use product rule. that's it

- anonymous

i need to know how to do it by ncr or npr can u hlp

- anonymous

and why (0-9)

- anonymous

can u tell me how to do it by ncr or npr@IrishBoy123

- anonymous

- anonymous

@ganeshie8 can u hlp

- anonymous

\[1C1 \times 10C1 \times10C1\times 2C1\]

- anonymous

ok thank u @ASAAD123

- anonymous

ok but why u do(0-9) why not(0-8) or any thing like this

- anonymous

0 is neither negative nor positive. sometimes is is counted as positive

- anonymous

ok but why u use 9 not other digit

- anonymous

there are only 10 digits (0,1,2,3,4,5,6,7,8,9)

- anonymous

ok why u chose 9 not 1 or 2 or 3or other digit

- anonymous

every number in the world is contained one or more of these digits.

- anonymous

for example:
1092
1912
1475

- anonymous

u chose 9 bec it is the end of the numer right or wrong

- anonymous

the end of digits

- anonymous

bec the numbers start from 0 to 9

- anonymous

ok digits from 0 to 9 rihgt or wrong

- anonymous

ok mr asaad can u tell me why u 1*10*10*2 and what is the Relationship between this and (0-9) that u wrote it 2nd

- anonymous

- anonymous

hlp

- mathmate

@Nourage
These nice people have been trying to help you do the counting, exactly as you posted "counting question".
Be patient and listen to the explanations. Calculations come later, when you understand how you count. In counting as in ALL math problems, blindly applying a formula does not work. You need to understand the problem first, then try to understand HOW you want to solve the problem. Formulas are just tools to help you when you need it.

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