1
7100

# Number System Questions for SSC CGL PDF:

Download Number system questions for SSC CGL Tier-1 and Tier-2 PDF. Maths number system questions for competitive exams like SSC CGL. Number System Questions with answers explained with detailed solutions and explanations using tricks.

Question 1:

The least number which when divided by 6, 9, 12, 15 and 18 leaves the same remainder 2 in each case is :

a) 180
b) 182
c) 178
d) 176

Question 2:

What is the arithmetic mean of first 20 odd natural numbers ?

a) 19
b) 17
c) 22
d) 20

Question 3:

The least number that should be added to 2055, so that the sum is exactly divisible by 27 is

a) 28
b) 24
c) 27
d) 31

Question 4:

The digit in the unit place in the square root of 66049 is

a) 3
b) 7
c) 8
d) 2

Question 5:

A certain sum will amount to 12,100 in 2 years at 10% per annum of compound interest, interest being compounded annually. The sum is

a) 8000
b) 6000
c) 12000
d) 10000

Solutions: 1 to 5

The numbers 6,9,12,15,18 leaves same remainder 2 in each case.
So, what we need to do is find the L.C.M. of these numbers and add 2 to it
L.C.M. of 6,9,12,15,18 = 180
=>Required no. = 180+2 = 182

NOTE :- Sum of first ‘n’ odd natural numbers = n^{2}
Sum of first ‘n’ even natural numbers = n(n+1)
Sum of first 20 odd natural numbers = 20^{2} = 400
Arithmetic mean = 400/20 = 20

The remainder obtained by dividing 2055 by 27 = 3
So, the least number that should be ‘subtracted’ from 2055 to make it perfectly divisible by 27 = 3
and the least number that should be added = 27-3 = 24

Square root of 66049 = 257

Thus, unit’s digit = 7

Amount after compound interest = $x (1 + \frac{10}{100})^{2}$ = 12100
=> $\frac{121x}{100}$ = 12100