FX quote question

Hi everyone,
I have been confused with the F/X quote since it appears among different subject.
I try to follow the rule “up to the bid, multiple. down to the ask, divide” in the certain template (USD/SGD) to figure out how should I use the quote. However, it appears in different way such as : USD per SGD, USD against SGD. Does anyone can provide a way I can remember to translate FX quote from the text into XX/XX so I can easily to calculate accordingly. Many thanks first.