on a piece of paper
Mary escreveu o seu número de telefone num pedaço de papel e o deu ao Tom.
Mary wrote her phone number on a piece of paper and gave it to Tom.
Escrevi meu nome num pedaço de papel.
I wrote my name on a piece of paper.
Encontrei essa mesma frase num pedaço de papel na casa de Phoenix.
I found that same phrase on a piece of paper in Phoenix's house.
— As Aventuras de Paddington 2 (2017)
Eu anotei o número de telefone dele num pedaço de papel.
I wrote his phone number down on a piece of paper.