I'm very impressed that you can divide 311 by 72 and get 4.3 - you must have done quite well in grade 5 maths.
However, if you read my post carefully you would've noticed that I said "about 5g", and I have included a definition of the word "about" for your benefit.
"about": Imprecise but fairly close to correct.
The current guidelines (the recommendations put together by the best dietitions, nutritionists, physiologists etc after consideration of the most current and most reliable research and statistics) state that the strength athlete should consume about (see definition above) 1.2-1.7g of protein per kg of bodyweight per day.
What this means - Consumption upwards of this recommendation yields no apparent physiological benefits - and some detrimental effects can come of consuming excessive amounts of protein - chance of kidney disease can be increased, dehydration can occur, COST can also become a big issue. The typical Australian diet already contains plenty of protein, and many Australians exceed their protein requirements without even trying. Although as someone training for strength and size your protein needs are increased somewhat - along with your energy requirements. It is FACT, however, that as you increase your energy intake - your protein intake increases accordingly (basically in a linear relationship) simply due to the proteins contained in the everyday foods you consume.
So basically, don't stress about drinking 78 protein shakes daily to get your 9.8142 kg of protein daily because that's what Joe Blogs said on the internet.
To the OP - be very careful about what you read and hear on the internet, the strength and conditioning industry is full of people giving their opinions, many of which are plain wrong.
I'm in no way claiming to be an expert or a professional, I'm just throwing up the most current guidelines.