11.
5358 x 51 = ?
A. 273258 B. 273268
C. 273348 D. 273358
Answer & Explanation
Answer: Option A
Explanation:
5358 x 51 = 5358 x (50 + 1)
= 5358 x 50 + 5358 x 1
= 267900 + 5358
= 273258.
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12.
The sum of first five prime numbers is:
A. 11 B. 18
C. 26 D. 28
Answer & Explanation
Answer: Option D
Explanation:
Required sum = (2 + 3 + 5 + 7 + 11) = 28.
Note: 1 is not a prime number.
Definition: A prime number (or a prime) is a natural number that has exactly two distinct natural number divisors: 1 and itself.
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13.
The difference of two numbers is 1365. On dividing the larger number by the smaller, we get 6 as quotient and the 15 as remainder. What is the smaller number ?
A. 240 B. 270
C. 295 D. 360
Answer & Explanation
Answer: Option B
Explanation:
Let the smaller number be x. Then larger number = (x + 1365).
x + 1365 = 6x + 15
5x = 1350
x = 270
Smaller number = 270.
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14.
(12)3 x 64 ÷ 432 = ?
A. 5184 B. 5060
C. 5148 D. 5084
E. None of these
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15.
72519 x 9999 = ?
A. 725117481 B. 674217481
C. 685126481 D. 696217481
E. None of these
Answer & Explanation
Answer: Option A
Explanation:
72519 x 9999 = 72519 x (10000 – 1)
= 72519 x 10000 – 72519 x 1
= 725190000 – 72519
= 725117481.
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16.
If the number 517*324 is completely divisible by 3, then the smallest whole number in the place of * will be:
A. 0 B. 1
C. 2 D. None of these
Answer & Explanation
Answer: Option C
Explanation:
Sum of digits = (5 + 1 + 7 + x + 3 + 2 + 4) = (22 + x), which must be divisible by 3.
x = 2.
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17.
The smallest 3 digit prime number is:
A. 101 B. 103
C. 109 D. 113
Answer & Explanation
Answer: Option A
Explanation:
The smallest 3-digit number is 100, which is divisible by 2.
100 is not a prime number.
101 < 11 and 101 is not divisible by any of the prime numbers 2, 3, 5, 7, 11.
101 is a prime number.
Hence 101 is the smallest 3-digit prime number.
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18.
Which one of the following numbers is exactly divisible by 11?
A. 235641 B. 245642
C. 315624 D. 415624
Answer & Explanation
Answer: Option D
Explanation:
(4 + 5 + 2) – (1 + 6 + 3) = 1, not divisible by 11.
(2 + 6 + 4) – (4 + 5 + 2) = 1, not divisible by 11.
(4 + 6 + 1) – (2 + 5 + 3) = 1, not divisible by 11.
(4 + 6 + 1) – (2 + 5 + 4) = 0, So, 415624 is divisible by 11.
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19.
(?) – 19657 – 33994 = 9999
A. 63650 B. 53760
C. 59640 D. 61560
E. None of these
Answer & Explanation
Answer: Option A
Explanation:
19657 Let x – 53651 = 9999
33994 Then, x = 9999 + 53651 = 63650
—–
53651
—–
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20.
The sum of first 45 natural numbers is:
A. 1035 B. 1280
C. 2070 D. 2140
Answer & Explanation
Answer: Option A
Explanation:
Let Sn =(1 + 2 + 3 + … + 45). This is an A.P. in which a =1, d =1, n = 45.
Sn = n [2a + (n – 1)d] = 45 x [2 x 1 + (45 – 1) x 1] = 45 x 46 = (45 x 23)
2 2 2
= 45 x (20 + 3)
= 45 x 20 + 45 x 3
= 900 + 135
= 1035.
Shorcut Method:
Sn = n(n + 1) = 45(45 + 1) = 1035.
2 2