How it's calculated
Official: $ 1.000.000,00 ÷ 274,3472 (Argentine pesos per real, dolarapi.com, 13/11/2026) = 3.645 R$. It's the bank reference; in a exchange house you're gonna get a little less by the margin.
Blue cross: If you have Argentine pesos in cash, the usual thing is to buy dollars from the blue ($ 1.570,00) and change them in Brazil; That's equal to 274,3472 Argentine pesos per real, that is 3.645 R$.
With a card: the consumption is charged to card dollar ($ 2.041,00), so give less: a few 2.804 R$. If you pay the summary with your own dollars, there's no advance tax collection.
A month ago, with $ 1.000.000 You were buying. 3.317 R$ to the official rate.