Penelope paid＄$$24.58$$ for pens and pencils. If pens cost $$9$$￠ each and pencils cost $$4$$￠ each, at most how many pens did Penelope purchase? 
Overseas Competition->Knowledge Point->Word Problem Modules->Unitary Method Problems->Applying Multiplication and Division
Continue subtracting $$4$$￠ from $$2458$$￠ until the difference is a multiple  of $$9$$. This happens when the difference is $$2430$$￠ which is $$270 \times 9$$￠. 