Investigate the questions in parts a and b by considering a number of examples
a. If a whole number is divisible both by 6 and by 2, is it necessarily divisible by 12?
b. If a whole number is divisible both by 3 and by 4, is it necessarily divisible by 12?
c. based on your examples, what do you think the answers to the questions in a and b should be?
d. Based on your answer to part c, determine whether 3,321,297,402,348,516 is divisible by 12 without using a calculator or doing long division. Explain your reasoning.