Research points calculation

[Emx77]

I'm having trouble calculating exact number of research points (RP). If I understands correctly, formula for RP is:

RP = (Allocated BP x bonus.1 x bonus.2 x ... x bonus.n)/BP cost for 1% of progress

Sometimes this formula gives me correct number of RP. However, sometimes it overestimates final number of RP as shown in attached screenshot. Why I get only 16 RP and not 18 RP in this example?

RP calculation.jpg (162.65 KiB) Viewed 280 times