Lost in Translation: The impossible task of buying 250g of bread in Brazil

-250 gr. de pão françes por favor.

Normally I would ask for a 1/4 kg but, remembering last time I tried, I decided 250grs. was more literal and easy to understand. 

The 2 attendants look at each other in puzzlement. Here we go, I thought. 

Attendant 1: -250gr.? Como assim?

Me: -Sim, 250gr., 1/4 de Kilo.

Attendant 1: -4Kg?!?

Me: -Não, um quarto de kilo. 250 grs.

I can't hide my smile.

One of the attendants suddenly brightens up and says in triumph to the other one:

-É mais ou menos 1/2 Kg! 500gr.

Me: -Não! é exatamente a metade disso. 250gr. 

Attendant 2: -Quantos pães? 4?

Me: -Sei la, começa a botar no saco que eu digo quando chega. 

She starts filling up a paper bag with bread.

Me: -Acho que deve ter 250grs aproximadamente ahi.

Attendant 2: -Mais e para botar 4kg, né?

I make sure they put it on the scale, so they understand what I meant. The scale reads 265 grs. They hand me the bag and I can tell they still didn't grasp the concept and think I'm a total wako.

Raf