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How many strings of three decimal digits

  1. do not contain the same digit three times?
  2. have exactly two digits that are 4s?

I know question is easy but the answer is not matching with the one given over here

Please someone verify..

Does the word β€œstring” mean that we can take 0 as the first digit as well?

closed with the note: Solved..
in Combinatory by Boss (23.5k points)
closed by | 61 views
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a)  do not contain the same digit three times = number of strings possible - contain the same digit three times

                                                                                         = 10 x 10 x 10 - 10 x 1 x 1

                                                                                         = 1000 - 10

                                                                                         =  990

b) have exactly two digits that are 4s =  1 x 1 x 9 x 3 =  27

I didn't open the link..

but is it correct ???
+1
Yes it is correct..

I didn't register the word "strings" and was calculating it by considering 3 digits decimal number :P
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@MiNiPanda hoye hoye :p

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@Magma πŸ˜‚πŸ˜‚

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