substate khan-exercises
Plotter: Change toFixedApprox to roundToApprox

Summary:
Stop changing whole numbers to decimals in the plotter

Test Plan:
 * Make a plotter
 * make sure that the numbers are 1 to 10 with no 1.00 etc.
 * change the 0.555
 * make sure every other number shows an approx sign

Auditors: alex