Elitmus
Exam
Logical Reasoning
General Mental Ability
Q. HOW MANY 4 DIGIT NO.CAN BE MADE WITH THE DIGITS 1,2,3,4,5,6,7 DIVISIBLE BY 25 ONLY ONCE?
Option
a) 20
b) 24
c) 60
d) Cant be determined
Read Solution (Total 16)
-
- only the digits ending with 25 and 75 are divisible by 25.
So, 5 should occupy the one's place (1)
either 2 or 7 should occupy the 10's place. 2
from the remaining numbers 1236(2 or 7) occupy 100's place. 5
and then in thousand's place 4
so, 4*5*2*1=40; - 11 years agoHelpfull: Yes(27) No(21)
- DIVISIBLE BY 25 ONLY ONCE means?
some digits 3125,4375 are divisible by 25 twice
so 40 cant be answer
ans 24
(b)
- 11 years agoHelpfull: Yes(27) No(12)
- DIGITS are 1,2,3,4,5,6,7
so no. is divisible by 25 only when last two digit is 25 or 75
DIVISIBLE BY 25 ONLY ONCE = TOTAL NO. DIVISIBLE BY 25 - NO. DIVISIBLE BY 625
=5*4*2*1-4*1
=40-4
=36 - 11 years agoHelpfull: Yes(9) No(3)
- nums divisible by 25 are 40 as we all know
nums divisible by 625 are:
----
units place is always 5----1 way
tens place can be 5,2,7..but 5 is already in units place..so it can be filled with 2 or 7 in---2 ways
hundreds place can be with 1,5,7..but 5 is already in units place..so it can be filled with 1 or 7 in---2 ways
thousands place in 4c1 ways..i.e 4 ways..
total 4*2*2=16
overall 40-16=24 - 10 years agoHelpfull: Yes(6) No(1)
- the ans would be 24(b). as the question says the num should be divisible by 25 only once that means it should not be divisible by 25*25 i.e. 625. so the ans will be obtained by( numbers div by 25- numb div by 625) i.e. 40-16=24
- 11 years agoHelpfull: Yes(5) No(2)
- to divide by 25 u must have 25,75 or 50 at right most side. so for right most position only one no. 5, for 10th position 2 or 7,100th-any of remaining 5 and 1000th only 4
so solution is 4*5*2*1=40 - 11 years agoHelpfull: Yes(4) No(5)
- its 20..
40-(the 4digit no. divisible by 75 ie.20) - 11 years agoHelpfull: Yes(1) No(2)
- from 40 we have to minus the numbers which is divisible by 625
- 11 years agoHelpfull: Yes(1) No(1)
- _ _ 25- (1,3,4,6,7)-5P2=20
_ _ 75- (1,2,3,4,6)-5P2=20
TOTAL=40 - 10 years agoHelpfull: Yes(1) No(0)
- it is divisible by only 25 but not with 625 and 15625 we observe that the first two places are not 5(4),6 and 25,75 so 3*4=12 again for 75 in last 3*4=12 24
- 10 years agoHelpfull: Yes(1) No(0)
- 40...... i slove this question in Elitmus exam
- 11 years agoHelpfull: Yes(0) No(13)
- we have 00,25,50,75 as possibilities that if the no. end with these it is div by 25.but 0 is not there so we have 25 and 75 as probability so 5c1*4c1+5c1*4c1=40
- 11 years agoHelpfull: Yes(0) No(3)
- it should not be 40 becoz only once we have to divide . from 40 we have to minus the numbers divisible by 75 and 125
- 11 years agoHelpfull: Yes(0) No(0)
- rakesh jee can u plz explain hw the ans is 24
- 11 years agoHelpfull: Yes(0) No(0)
- rakesh please explain your answer
- 11 years agoHelpfull: Yes(0) No(0)
- @rakesh
what about option a and d then?
- 11 years agoHelpfull: Yes(0) No(0)
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