Hello Donald, I punched in several senarios with the calculator and i believe you are right. You don't get the exact figure but close enough. The board has random white areas with a random pattern. For the multiplying by 3 to be correct the white areas must be one third of the whole. The squares number 15 across and 18 down and are the same size as the sticky boards i get from the state. The Dewill Varroa mite detector insert i use at times has the same size square but is 13 squares down by 11 squares across (143 total). I suppose if you blacked out 2/3 of the squares(approx 95). Counted the mites on the unblacked squares and (as Donald said) multiplied by 3 you would get the same basic result with less trouble. Thanks Donald. I have allways been counting all the mites when i want to be exact. With the Penn State *varroa board* it would be hard to count the mites on the black squares. Next spring i will test the Penn State *varroa board* against the *dewill insert* and see how accurate averaging is. I must admit i have pulled inserts with more mites on it than i would care to count. The Penn State board has a reusable feature as it is laminated. The instructions say: Cover this board with a thin layer of petroleum jelly;scrape off and re-coat to reuse. Clever idea! Also if you wanted to count all the mites you could scrape onto a white piece of paper and then count. Mine was given to me by a fellow beekeeper but i imagine the *varroa board* is for sale through the Pennsylvania State Bee Lab although i didn't find info on the boards at their web site. I have been through many cases of the dewill inserts and cases of ones i have made with white paper. Maybe these laminated *varroa boards* would be a wise investment for the serious beekeeper. Sincerely, Bob Harrison Donald wrote; > When you get a total mite number, divide that number by 90. Now > multiply the answer by 270 and you have the total number of mites on > the board. > > Would this be the same as multiplying by 3? > > Best regards, > > Donald Aitken > Edmonton Alberta Canada