What is a controlled experiment?
a. two variables are changed at a time
b. all variables are kept constant
c. none of the variables are changed
d. one variable is changed at a time

The plum pudding model of the atom states that ?

At very high pressures, gases become and will eventually a) more dense; become hotter b) more dense; change to a liquid or solid c) less dense; combust d) less dense; turn into a liquid

Write the function getkthdigit(n, k) that takes a possibly-negative int n and a non-negative int k, and returns the kth digit of n, starting from 0, counting from the right