Khan/khan-exercises — pull request #5753 by haleret (2011-11-07 22:13:53+00:00)
Title: si_quantity answer type and exercise for Circuits I video (Ohm's law)

* si_quantity answer type: translates answer into base SI units before comparing, so "10 cm" and "0.1 meter" are equivalent answers
* scientific notation math-format helpers: Functions to calculate the mantissa, exponent for the scientific notation of floating-point values
* roundToSignificant: Rounds a number to the specified number of significant digits, regardless of their position
* New exercise: Ohm's Law - Asks students to solve for any single unknown in a basic Ohm's Law problem; corresponds with the Circuits I video in the Physics playlist