Big Picture has a post on how the number .4 does not show up much in earning. It seems that 0.4 is close enough to 0.5 so numbers are "massaged" to raise it so that earnings can be rounded up.
A lot of industries manipulate numbers the same way in proposals to make things look good. In the mining industry, especially gold mining, manipulation of numbers has a much larger effect on earnings. I say gold because the concentration of gold in gold reserves has grossly declined. It means that costs have sky rocketed because you have to grind more tons to get the same amount of gold.
I did an analysis on the increasing cost of declining reserves in terms of mining in my post "Declining Grade of Ore: Are the Cost Disadvantages Linear?" The graphs in there show how much a half gram difference in gold grade changes the percent cost just based on how much more rock you have to mine and mill to get the same amount of gold. So, wee bit of fudging the numbers with crap reserve quality has enormous implications for investors in how much the estimate costs can be out. I will just quote what I said in the post:
I would suggest that what it means is that anyone signing their name saying that a low-grade reserve is economically viable is either incompetent, unethical or they think investors are truly gullible and stupid.
I have not looked at it in a while, but the trend had been to fudge the numbers to bring previously uneconomical resource in the reserves making the company look better.