to become lower in value

devalue, lose value

(to cause the value of a currency) to become less (especially in exchange for other currencies)

depreciate

a small amount; to make a quick written note of it

scribble down

to put another price on (something); to increase the exchange value of (money)

depreciate

to make letters or other symbols on a surface, especially with a pen or pencil on paper

put language down on paper

of write

put language down on paper