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If x, y and z are distinct prime numbers, then their LCM is __

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Important Questions on Number Theory

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Mathematics>Arithmetic>Number Theory>Prime Numbers
Find the smallest positive integer n≥10 such that n+6 is a prime and 9n+7 is a perfect square.
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Mathematics>Arithmetic>Number Theory>Prime Numbers
A two-digit number ab¯ is called almost prime if one obtains a two-digit prime number by changing at most one of its digits a & b. (For example, 18 is an almost prime number because 13 is a prime number). Then the number of almost prime two-digit numbers is
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Mathematics>Arithmetic>Number Theory>Prime Numbers
There are four prime numbers written in ascending order. The product of the first three is 385 and that of the last three is 1001. The last number is :
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Mathematics>Arithmetic>Number Theory>Prime Numbers
The prime numbers a, b and c are such that a+b2=4c2. Determine the sum of all possible values of a+b+c.
MEDIUM
Mathematics>Arithmetic>Number Theory>Prime Numbers
For an integer n, let Sn=n+1,n+2,…., n+18. Which of the following is true for all n≥10 ?
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Mathematics>Arithmetic>Number Theory>Prime Numbers
Let N denote the number of all natural numbers n such that n is divisible by a prime p>n and p<20. What is the value of N?
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Mathematics>Arithmetic>Number Theory>Prime Numbers
A prime number p is called special if there exist primes p1, p2, p3, p4 such that p=p1+p2=p3-p4.
The number of special primes is
 
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Mathematics>Arithmetic>Number Theory>Prime Numbers
Express 120 as a product of its prime factors.
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Mathematics>Arithmetic>Number Theory>Prime Numbers
Which of the following number is an odd and prime number?
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Mathematics>Arithmetic>Number Theory>Prime Numbers
The sum of the squares of the digits of the largest two-digit prime number is:
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Mathematics>Arithmetic>Number Theory>Prime Numbers
If a and b are positive integers such that a2-b2 is a prime number, then a2-b2 is equal to:
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Mathematics>Arithmetic>Number Theory>Prime Numbers
The number of 6-digit numbers of the form ababab (in base 10) each of which is a product of exactly 6 distinct primes is
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Mathematics>Arithmetic>Number Theory>Prime Numbers
It is given that the number 43361 can be written as a product of two distinct prime numbers p1, p2. Further, assume that there are 42900 numbers which are less than 43361 and are co-prime to it. Then, p1+p2 is
MEDIUM
Mathematics>Arithmetic>Number Theory>Prime Numbers
Consider the set E={5,6,7,8,9}. For any partition {A,B} of E, with both A and B non-empty, consider the number obtained by adding the product of elements of A to the product of elements of B. Let N be the largest prime number among these numbers. Find the sum of the digits of N.
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Mathematics>Arithmetic>Number Theory>Prime Numbers
Express 120 as a product of its prime factors.
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Mathematics>Arithmetic>Number Theory>Prime Numbers
The number of prime numbers which are less than 100 is:
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Mathematics>Arithmetic>Number Theory>Prime Numbers
For a,b∈0,1,⋯,9, a two digit number ab is defined for 10a+b. A two digit number ab is called a special prime if both ab and ba are primes. Then the total number of special primes is
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Mathematics>Arithmetic>Number Theory>Prime Numbers
Which of the following is not a pair of prime numbers ?
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Mathematics>Arithmetic>Number Theory>Prime Numbers
Suppose a,b,c are positive integers such that 2a+4b+8c=328. Then a+2b+3cabc is equal to-
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Mathematics>Arithmetic>Number Theory>Prime Numbers
If a and b are positive integers such that a2-b2 is a prime number, then