I rated it 4 stars because ratings of 4.8 or 4.9 were not available. I couldn't give it 5 because of the error in the result putting the interest earned at a whopping $1577.75 with a minuscule interest of 0.75% after only a measly 85 days! This a 100.17% increase! whew! Obviously this is a silly error which math teachers are quite fond of penalizing more severely.
So take 4.9 stars for an otherwise exceptionally clear and concise explanatory example of a potentially complex topic in which other sites failed miserably.