Elitmus
Exam
Numerical Ability
Number System
how many numbers are there below 1000 which are neither perfect square nor perfect cube?
A) 961
B)958
c)955
D) not remb
Read Solution (Total 13)
-
- 31^2= 961 and 32^2= 1024... so square of 1 to 31 is less than 1000.
Again 10^3= 1000.... so cube of 1-9 are below 1000.
So, total no. of perfect square and perfect cube is (31+9)-1 [as 1 is common for both].
So the ans is 1000-39= 961 - 9 years agoHelpfull: Yes(38) No(16)
- ans :962
for numbers 1 to 31 there are squares below 1000
for numbers 1 to 9 there are squares below 1000
square and cube of 1 is 1 , 4*4*4=64 and 8*8=64,9*9*9=729 and 27*27=729 so we have to consider it thrice
then 31+9=40-3=37
ans 962 - 9 years agoHelpfull: Yes(33) No(5)
- 962 is the right answer
because there are 31 digits having square below 1000
and 9 digits having cubes below 1000
and 1,64,729 are counted twice so u have to subtact these choices
- 9 years agoHelpfull: Yes(10) No(0)
- Total no of squares of a number below 1000 are 31
Total no of cubes below 1000 are 9 in which 1 ,64, 729 already taken in squares.so required no = 999-31-6=962 - 9 years agoHelpfull: Yes(10) No(0)
- ans :961
for numbers 1 to 31 there are squares below 1000
for numbers 1 to 9 there are squares below 1000
square and cube of 1 is 1 so we have to consider only once
then 31+9=40-1=39
ans 961 - 9 years agoHelpfull: Yes(5) No(6)
- cubes of no 1 to 9 less than 1000 = 9 nos
squares of no 1 to 31 less than 1000= 31 nos
the coinciding cubes and squares are ^ 6 therefore 1^6 ,2^6,3^6 =3 nos
total nos =31+9-3=37
nos below 1000 therefore from 999
999-37=962 ans - 9 years agoHelpfull: Yes(5) No(0)
- @gona 962 is given in options.
- 9 years agoHelpfull: Yes(1) No(0)
- @SUDHEER KUMAR 'MORON' ques is below 1000 so ans will be 962 at least read ques properly before solving
- 9 years agoHelpfull: Yes(1) No(0)
- We use the Inclusion-Exclusion Principle. There are 1000 integers from 1 to 1000;
among these numbers, 31 are perfect squares (indeed, 312 = 961 ≤ 1000, but 322 > 1000), 10 are perfect cubes (this is because 103 = 1000), and 3 are both squares and cubes (these three numbers are 16 = 1, 26 = 64, and 36 = 729). Thus, by the Inclusion-exclusion principle, there are
1000 − (31 + 10) + 3 = 962
numbers that are neither perfect squares nor perfect cubes. - 7 years agoHelpfull: Yes(1) No(1)
- 962 is not given in options surely..option d is either 956 or 949
- 9 years agoHelpfull: Yes(0) No(1)
- the ans is 958 bcoz we have 10 cubes below 1000 and square are 32 so from 1000 minus these number we get ens 1000-42=958
- 9 years agoHelpfull: Yes(0) No(2)
- 1,2,4,8,9,16,25,27,36,49,64,81,100,121,125,144,169,196,216,225,256,289,324,343,361,400,441,484,512,529,576,625,676,729,784,841,900,961=== total 38 numbers...so anwwer is 962
- 9 years agoHelpfull: Yes(0) No(0)
- 1 and 64 are common for both square and cube.
so it should be 31(for square numbers)+9(for 1-9 cube numbers)-2=38
Is it correct? - 9 years agoHelpfull: Yes(0) No(3)
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