Nthawi zambiri, mukamagwira ntchito ndi manambala, muyenera kuwerengera peresenti. Kuwerengera uku kumagwiritsidwa ntchito kudziwa kuchotsera, kutsatsa malonda, kuwerengera kuchuluka kwa VAT ndi mawerengedwe ena ambiri.
Mu phunziro lotsatirali lokhudza kugwira ntchito mu Microsoft Excel, tisanthula mwatsatanetsatane momwe tingachulukitsire manambala ndi peresenti.