Latest self Aptitude Question SOLUTION: how many nos divisible by 25 can be formed with 0,1,2,3,4,5,6,7 if repetition of digits not allowed??

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how many nos divisible by 25 can be formed with 0,1,2,3,4,5,6,7 if repetition of digits not allowed??

naina (11 years ago)

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Jasmine Khan  (11 years ago)

Naina i think the answer that i have written is currect because
we will choose 0 and 5 at the unit place write.
now we are left with 1,2,3,4,6,7 numbers.
at first place we will chose one number out of 6.i.e. 6C1
at second place we will chose one number out of remaining 5 numbers i.e.5C1
and so on.
but last place that is the unit place will contain either 0 or 5 i.e. 2C1
therefore total number=6C1*5C1*4C1*3C1*2C1*1C*2=1440

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Jasmine Khan  (11 years ago)

the number which is divisible by 25 must have 0 or 5 at its unit place.
so the remaining 6 numbers can be arrange in 6! ways and 0 & 5 can be arrange in 2! ways.
therefore the total numbers divisible by 25=6!*2!=720*2=1440
hence there are 1440 number made by using 0,1,2,3,4,5,6,7 and are divisible by 25.

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naina  (11 years ago)

ans is 2160 but how???

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