Elitmus
Exam
Numerical Ability
Number System
how many numbers are there whose factorial ends with 17 zeros
a)6 b)5
c)0 d)11
Read Solution (Total 6)
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- answer c :)
checking no. of zeros
=70/5 + 70/25 = 14+ 2 =16 zeros
=75/5 + 75+25 = 15 + 3 = 18 zeros
similarly 71,72,73,74 have 16 zeros
and after 75! have more than 18 zeros..
so there is no number ... - 11 years agoHelpfull: Yes(51) No(1)
- answer =option C)0
70!=ends with 16 zeros
so as 71!,72!,73!,74! ends with 16 zeros
but 75! ends with 18 zeros
so there is no number possible whose factorial has 17 zeros at end
- 11 years agoHelpfull: Yes(23) No(1)
- in 70! number of zero=14+2=16
in75! zero=15+3=18
so 17 zero in factorial no number available - 11 years agoHelpfull: Yes(5) No(1)
- it's simple called factorial jump which happens at 25 50 75 100 ..... u beeter remeber these fundas
- 11 years agoHelpfull: Yes(1) No(8)
- the formula for finding number of zeros in n! is
[n/5]+[n/5^2]…[n/5^r] - 11 years agoHelpfull: Yes(0) No(2)
- lets 5!=ends with one zero
6!,7!,8!,9! also ends with one zero (czee these are multipli in 5!).
10!=ends with double zero.
so,
ends with one zero=5 (such number)
so that after every 5 numbers one zero add.
option (b) ans - 8 years agoHelpfull: Yes(0) No(0)
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