I have 4 hard questions here: What is x% of x?

In how how many of the ordered pairs of positive integers ( x, y ) that satisfy 2x + 3y = 9 999 999 999 999 is a x a prime number?

Each of the letters t, h, a, n, k, and s is assigned a different one of the values 1, 2, 3, 4, 5, and 6. What is the least possible value of t to the 1st power, h to the 2nd power, a to the third power, n to the 4th power, k to the 5th power, and s to the 6th power?

How many integers greater then 1 million and less than 4 million are squares of integers?