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Earn 100

Let E denote the set of all natural numbers n such that 3<n<100 and the set {1,2,3,,n} can be partitioned into 3 subsets with equal sums. Find the number of elements of E.

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Important Questions on Number Theory

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IMPORTANT
Consider the sequence of numbers n+2n+12 for n1, where x denotes the greatest integer not exceeding x. If the missing integers in the sequence are n1<n2<n3<.., then find n12.
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Let a1=24 and form the sequence an, n2 by an=100an-1+134. The first few terms are 24, 2534, 253534, 25353534, ..... What is the least value of n for which an is divisible by 99?
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Let N be the smallest positive integer such that N+2N+3N+.........+9N is a number all whose digits are equal. What is the sum of the digits of N?
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Let sn denote the sum of the digits of a positive integer n in base 10. If sm=20 and s33m=120, what is the value of s3m ? 
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Let Fka,b=a+bk-ak-bk and let S=1,2,3,4,5,6,7,8,9,10. For how many ordered pairs a,b with a, bS and ab is F5a, bF3a, b an integer?
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Let N be the number of ways of choosing a subset of 5 distinct numbers from the set 10a+b:1a5,1b5, where a, b are integers, such that no two of the selected numbers have the same unit's digit and no two have the same ten's digit. What is the remainder when N is divided by 73?

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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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IMPORTANT
Let a, b, c be distinct positive integers such that b+c-a, c+a-b and a+b-c are all perfect squares. What is the largest possible value of a+b+c smaller than 100?