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madhu.mukherjee.946

  • one year ago

find the number of numbers less than 1000 and divisible by 5 which can be formed with the digits 0 1 2 3 4 5 6 7 8 9 without repetition

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  1. madhu.mukherjee.946
    • one year ago
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    @imqwerty

  2. madhu.mukherjee.946
    • one year ago
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    @imqwerty fast :P

  3. madhu.mukherjee.946
    • one year ago
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    you are taking too long such a small sum:)

  4. imqwerty
    • one year ago
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    a number divisible by 5 has either 5 at end or 0 at end so total such number will include all numbers of 1 digit , 2 digits... 1 digit nos are easy to count they are-5 2 digits nos - we consider 2 cases one with 0 at the end and one with 5 at the end A A] 0 at the end 1st place can be filled with-1,2,3,4,5,6,7,8,9 and 0 is fixed at 2nd place so total numbers=9x1=9 B]5 at end 1st place can be filled with-1,2,3,4,6,7,8,9=8nos we didn't take 0 cause then it wuld be a single digit no we also didn't take 5 cause its already set at 2nd place so total nos=8x1=8 total 2 digit nos=17 3 digit nos- A] 0 at end 1st place can be filled with-1,2,3,4,5,6,7,8,9=9nos 2nd place can be filled with 8 nos cause 1 number will be consumed in this^ step=8nos left to fill 2nd place 3rd place has 0=1no so total combinations =9x8 B] 5 at end 1st place can be filled with-1,2,3,4,6,7,8,9=8nos 2nd place can be filled with 8 nos cause we can take 0 here along with the 7 digits left after filling 1st place=8nos 3rd place has 5 =1no total nos=8x8 total 3 digit nos=72+64=136 total nos=136+17+9 =162

  5. madhu.mukherjee.946
    • one year ago
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    wrong answer is 154

  6. imqwerty
    • one year ago
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    i wrote in brief :D

  7. imqwerty
    • one year ago
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    lol wait

  8. imqwerty
    • one year ago
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    hey i did that correct i jst made calculation mistake :P its 72+64+17+1=154

  9. imqwerty
    • one year ago
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    i wrote that 9 by mistake :)P total i digit nos=1 total 2 digit nos=17 total 3 digit nos=72+64 total=154 >.<

  10. imqwerty
    • one year ago
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    *1 digit nos

  11. madhu.mukherjee.946
    • one year ago
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    how did you get the 3 digit numbers pls explain

  12. ribhu
    • one year ago
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    the three digit numbers are obtained taking into account two cases

  13. madhu.mukherjee.946
    • one year ago
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    yeah 0 and 5

  14. madhu.mukherjee.946
    • one year ago
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    i got the 0 part just explain me the the 5 part

  15. ribhu
    • one year ago
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    first 0: the first digit can be filled with 9 choices.. second will be 8 and since 0 is fixed so we get 9*8 = 72 numbers ending in 0 with three digits

  16. madhu.mukherjee.946
    • one year ago
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    yeah even i got that

  17. ribhu
    • one year ago
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    see 5 is fixed.. so first digit can be filled in 8 ways..since 0 can not come in first place so second has 8 options..every number except for 5: so we have 8*8 = 64

  18. ribhu
    • one year ago
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    |dw:1443975974588:dw|

  19. madhu.mukherjee.946
    • one year ago
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    yeah thank you so much i got that

  20. madhu.mukherjee.946
    • one year ago
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    even i calculated this way and found out .mine answer matches with u

  21. imqwerty
    • one year ago
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    (:

  22. madhu.mukherjee.946
    • one year ago
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    thanks imqwerty : today i saw u sitting on top of the roof of your school with a monkey:P @imqwerty

  23. madhu.mukherjee.946
    • one year ago
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    :)))))))))))))))

  24. imqwerty
    • one year ago
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    (: that monkey ws talkin wid me abt u

  25. madhu.mukherjee.946
    • one year ago
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    ahhhhhhhhhhhhh

  26. imqwerty
    • one year ago
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    yea :) he ws tellin that u 2 made a plan to go out but i came in middle e.e

  27. madhu.mukherjee.946
    • one year ago
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    ooo very funny:P

  28. imqwerty
    • one year ago
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    shuld i leave u 2 alone or be here e.e

  29. madhu.mukherjee.946
    • one year ago
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    @imqwerty i'll kill you

  30. imqwerty
    • one year ago
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    omg looool XD please kill me fast

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