[discodermolide]

hi....

i want to calculate no. of moles absorbed in absorber which is after 3rd bed..

OK according to your table a total of 43.159 Kmoles of SO₃ has been produced at the third bed, assuming no losses this goes into the absorber after the third bed, therefore if absorption is 100% then you have 43.159 Kmoles of SO₃ in the absorber.
I don't see what the problem is?