[B].
[C].
[D].
Answer: Option D
Explanation:
The square of a natural number nerver ends in 2.
143642 is not the square of natural number.
[B].
[C].
[D].
Answer: Option A
Explanation:
The sum of two odd number is even. So, a + b is even.
[B].
[C].
[D].
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.
[B].
[C].
[D].
Answer: Option C
Explanation:
437 > 22
All prime numbers less than 22 are : 2, 3, 5, 7, 11, 13, 17, 19.
161 is divisible by 7, and 221 is divisible by 13.
373 is not divisible by any of the above prime numbers.
373 is prime.
[B].
[C].
[D].
Answer: Option D
Explanation:
91 is divisible by 7. So, it is not a prime number.
[B].
[C].
[D].
Answer: Option D
Explanation:
Clearly, 97 is a prime number.
[B].
[C].
[D].
Answer: Option B
Explanation:
Prime numbers less than 50 are:
2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47
Their number is 15
[B].
[C].
[D].
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.
[B].
[C].
[D].
Answer: Option B
Explanation:
The smallest prime number is 2.
[B].
[C].
[D].
Answer: Option B
Explanation:
Unit digit in 795 = Unit digit in [(74)23 x 73]
= Unit digit in [(Unit digit in(2401))23 x (343)]
= Unit digit in (123 x 343)
= Unit digit in (343)
= 3
Unit digit in 358 = Unit digit in [(34)14 x 32]
= Unit digit in [Unit digit in (81)14 x 32]
= Unit digit in [(1)14 x 32]
= Unit digit in (1 x 9)
= Unit digit in (9)
= 9
Unit digit in (795 – 358) = Unit digit in (343 – 9) = Unit digit in (334) = 4.
So, Option B is the answer.