Multiple choice A positive integer is subtracted from its square. Which of the following could be the units digit of the final result?

Multiple choice When the positive integer m is divided by 7, the remainder is 4. What is the remainder when 2m is divided by 7 ?

Q&A If a and b are numbers such that (a − 4)(b + 6) = 0, then what is the smallest possible value of a^2 + b^2 ?

Multiple choice A particular integer N is divisible by two different prime numbers p and q. Which of the following must be true?I. N is not a prime number.II. N is divisible by pq.III. N is an odd integer.