What is the total number of chromosomes in an endosperm cell (of corn) after the first round of cell division

Endosperm of corn is typically triploid, so there would be a total of 30 chromosomes in normal endosperm cells.  This is because endosperm is fomred from one pollen cell (sperm) and 2 polar bodies (female).  If the endosperm cells were cultured in a solution containing colchicine and allowed to undergo one round of cell division, the viable cells would contain 6 sets of chromosomes (60 chromosomes total or 6n).  The reason for this is that colchicine is a nasty chemical that inhibits spindle formation during mitosis and as a result, the duplicated chromosomes are not pulled into separate dughter cells.  Colchicine is used to generate plants referred to as "double haploids".