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Is 1 a prime number ?

Important Questions on Playing with Numbers

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Mathematics>Arithmetic>Playing with Numbers>Prime and Composite Numbers
The number of positive integers n in the set 2,3,…..,200 such that 1n has a terminating decimal expansion is
MEDIUM
Mathematics>Arithmetic>Playing with Numbers>Prime and Composite Numbers
How many natural numbers n are there such that n!+10 is a perfect square ?
MEDIUM
Mathematics>Arithmetic>Playing with Numbers>Prime and Composite Numbers
There are exactly twelve Sundays in the period from January 1 to March 31 in a certain year. Then, the day corresponding to February 15 in that year is
MEDIUM
Mathematics>Arithmetic>Playing with Numbers>Prime and Composite Numbers
The largest non-negative integer k such that 24k divides 13! is
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Mathematics>Arithmetic>Playing with Numbers>Prime and Composite Numbers
The number of prime numbers which are less than 100 is:
HARD
Mathematics>Arithmetic>Playing with Numbers>Prime and Composite Numbers
Let n>1 be an integer. Which of the following sets of numbers necessarily contains a multiple of 3?
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Mathematics>Arithmetic>Playing with Numbers>Prime and Composite Numbers

Consider the following statements: For any integer n, 

I.. n2+3 is never divisible by 17 .

II.. n2+4 is never divisible by 17. Then

 

HARD
Mathematics>Arithmetic>Playing with Numbers>Prime and Composite Numbers
For a real number r let r denote the largest integer less than or equal to r. Let a>1 a real number which is not an integer and k be the smallest positive integer such that ak>ak Then which of the following statement is always true?
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Mathematics>Arithmetic>Playing with Numbers>Prime and Composite Numbers
Consider the pairs of prime numbers (m, n) between 50 and 100 such that m-n=6. How many such pairs are there?
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Mathematics>Arithmetic>Playing with Numbers>Prime and Composite Numbers
One fourth of the sum of the prime numbers, greater than 4 but less than 16, is the square of
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Mathematics>Arithmetic>Playing with Numbers>Prime and Composite Numbers
The number of digits in the decimal expansion of 165516 is
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Mathematics>Arithmetic>Playing with Numbers>Prime and Composite Numbers
The sum of the squares of the digits of the largest two-digit prime number is:
HARD
Mathematics>Arithmetic>Playing with Numbers>Prime and Composite Numbers
The function f :N→I defined by fx=x-5x5 , where N is the set of natural numbers and x denotes the greatest integer less than or equal to x, is:
MEDIUM
Mathematics>Arithmetic>Playing with Numbers>Prime and Composite Numbers
The number of distinct primes dividing 12!+13!+14! Is
HARD
Mathematics>Arithmetic>Playing with Numbers>Prime and Composite Numbers
For a real number r we denote by r the largest integer less than or equal to r. If x, y are real numbers with x, y ≥1 then which of the following statements is always true?
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Mathematics>Arithmetic>Playing with Numbers>Prime and Composite Numbers

The sum of three consecutive numbers is 126. Find the highest number-

1. 41
2. 42
3. 43
4. 44

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Mathematics>Arithmetic>Playing with Numbers>Prime and Composite Numbers

How many times does the number 3 occur in unit's place for numbers ranging from 1 to 100?

1. 20
2. 11
3. 10
4. 19

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Mathematics>Arithmetic>Playing with Numbers>Prime and Composite Numbers
Find the mean of the first 6 prime numbers.
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Mathematics>Arithmetic>Playing with Numbers>Prime and Composite Numbers
Which of the following is not a pair of prime numbers ?
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Mathematics>Arithmetic>Playing with Numbers>Prime and Composite Numbers
Which of the following number is an odd and prime number?