1).(1015)2 = ? (A) 1040125 (B) 1030225
(C) 1050125
(D) 1025125 Answer:(B) Explanation: 10152 = (1000+15)2
= 10002 + 152 +2 x 1000 x 15 2).Which one is NOT divisible by 3 ? (A) 5271 (B) 6291 (C) 4372 (D) 8952 Answer:(C) Explanation:
If the total of digits is divisibble by 3, number is also divisible by 3
5271……..5+2+7+1=15 is divisible by 3
6291……..6+2+9+1=18 is divisible by3
4372……..4+3+7+2=16 is not divisible by 3
8952……..8+9+5+2=24 is divisible by 3 3).Largest five digit number exactly divisible by 39 is: (A) 99979 (B) 99956 (C) 99989 (D) 99996 Answer:(D)
Explanation: Largest 5 digit number is 99999.
Let us divide 99999 by 39
39) 99999 (2564
78
-----
219
195
-----
249
234
-----
159
156
----
3
From above calculation, we know 39*2564 + 3 = 99999
Therefore 99999-3 = 99996 is the largest divisible number by 39. 4).Which is not the prime number? (A) 43 (B) 57 (C) 73 (D) 101 Answer:(B) Explanation: A positive natural number is called prime number if nothing divides it except the number itself and 1. 57 is not a prime number as it is divisible by 3 and 19. 5).103 x 103 + 97 x 97 = ?
(A) 21348
(B) 20018
(C) 19648
(D) 21428
Answer: (B)
Explanation: 103 x 103 + 97 x 97
= (100+3)2 + (100-3)2
= 2 (1002 + 32 )
[ (X +Y)2 + ( X – Y)2 = 2 ( X2 + Y2 ) ]
= 2 (10000 + 9 )
= 2 x 10009
= 20018 6).9848 x 125 = ?
(A) 1232000
(B) 1242000
(C) 1231000
(D) 1233000
Answer: (C)
Explanation: 9848 x 125 = 9848 x (250 / 2)
= 4924 x (500 / 2)
= 2462 x (1000 / 2)
= 1231 x (1000)
= 1231000
7).How many of the following numbers are divisible by 9
96381, 46729, 54459, 85369, 46818 (A) 1
(B) 2
(C) 4
(D) 3
Answer: (D)
Explanation: If sum of digits are divisible by 9, number is also divisible by 9 96381…..9+6+3+8+1= 27 (/)
46729…..4+6+7+2+9= 28 (x)
54459…..5+4+4+5+9= 27 (/)
85369…..8+5+3+6+9= 31 (x)
46818…..4+6+8+1+8= 27 (/) 8).What will be the next number?
3, 5, 7, 11, 13, 17……. (A) 21
(B) 19
(C) 25
(D) 20
Answer: (B)
Explanation: This is a sequence of prime numbers

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