## To Do

1. Write a sketch that prints out all the vowels in the English alphabet on the
same line. Then modify the sketch so that it prints the vowels out on separate lines.

2. Write a sketch that prints the circumference and area of a circle with a radius
of 1.0. Print results with a precision of 3 digits after the decimal place.

3. Write a sketch that prints out the clock speed of the microprocessor. (Bit hint:
this value is stored in a constant called `F_CPU`.) Also print out the number of
seconds for each tick of the microprocessor’s clock. (Another hint: the time
per tick is just 1/F_CPU.) (Yet another hint: you will need quite a bit of
precision to see the clock time, which is a very small number.)

4. Write a sketch to print out a multiplication table. The table should
print all the products of `(i*j)`, where `i` and `j` each range from 0 through 9.

5. Write a sketch to print out a division table. The table should
print all the quotients of `(i/j)`, where `i` and `j` each range from 1 through 9.