21. The sum of n different positive integers is less than 100. What is the greatest possible value of n?
22.If p is a prime number greater than 11, and p is the sum of the two prime numbers x and y, then x could be which of the following?
23.Of the positive integers that are multiples of 30 and are less than or equal to 360, what fraction are multiples of 12?
24.If x, y and z are consecutive integers and x
(1). xyz is even.
(2). x+y+z is even.
(3).(x+y)(y+z) is odd.
25.The product of two consecutive positive integers cannot be
A. a prime number
B. divisible by 11
C. a multiple of 13
D. an even number less than 10
E. a number having 4 as its units digit.
26.When a certain number is divided by 7, the remainder is 0. If the remainder is not 0 when the number is divided by 14, then the remainder must be
27.How many of the positive integers less than 25 are 2 less than an integer multiple of 4?
28. If y is the average (arithmetic mean) of n consecutive positive integers, n>1,what is the sum of the greatest and least of these integers?
29.A positive integer with exactly two different divisors greater than 1 must be
A. a prime
B. an even integer
C. a multiple of 3
D. the square of a prime
E. the square of an odd integer
30.What is the least prime number greater than 83?