Take EUR/USD for example. 1 Euro = 1.3 USD.
So shouldn’t the ratio, EUR/USD, = 1 Euro divided by 1.3 USD?
So why does EUR/USD = 1.3 and not .77 ?
wtf?
No… 1 eur divided by 1 usd = 1.30 —> eur/usd=1.30
If we assume eur is equal to 1… Then usd has to be less the 1 as its value is less then the euro… If its less then one, then 1 divided by a number less the one will result in a number greater then one… In this case… 1.30
It’s not really a math equation anyways… It’s an exchange rate… It is just nomenclature… If you read it as “euros per dollar” then yes it’s upside but that is the incorrect way to read it… It should be read as “the value of the Eur compared to the dollar”.
"[I]So shouldn’t the ratio, EUR/USD, = 1 Euro divided by 1.3 USD?[/I]"
No, because then you would be calculating EUR/(EUR/USD)
The division is of relative worth.
You could think of it as on the world market 1 Euro may buy 13 potatoes, whereas 1 USD may only buy 10
So EUR is worth 13 potatoes and USD is worth 10 potatoes
So Euro compared to the USD is 13 potatoes/10 potatoes.
Yes, small potatoes,I know 
EUR (the first currency always) is the base currency
USD (the second always) is the counter currency
EUR/USD means how much is worth the euro against the dollar
if bigger then 1 than the euro is better,smaller than 1 then the dollar is better
if the rate is 1 that means they have the same value
an 1.3 exchange rate means u can buy 1 euro if you have 1$ and 30 cent
an 0.77 exchange rate means u can buy 0.77 euro if you have 1$
its that simple