In the division expression $$28\div$$~\uline{~~~~~~~~~~}~$$=$$~\uline{~~~~~~~~~~}~$$\text{r}4$$, how many different pairs of number are there to fill the gaps? 
Overseas Competition->Knowledge Point->Number Theory Modules->Remainder Problems
We can use the equation: divisor $$\times$$ quotient $$=$$ dividend $$-$$ remainder, so here we can get divisor $$\times$$ quotient $$=28-4=24$$. Therefore, the only possibilities are $$1$$ and $$24$$, $$2$$ and $$12$$, $$3$$ and $$8$$, and $$4$$ and $$6$$ for a total of four possible combinations. 