In chapter 5 when he said "3Q" it means as Thank you.. This is how some japanese said it because 3 in japanese is San and when both 3Q are together they pronounce it as SanQ..
And if you as why is means thank you, this is because they cannot pronounce "Thank" as how english speaker pronounce it and when they try it will sound like San instead of Thank
In chapter 5 when he said "3Q" it means as Thank you.. This is how some japanese said it because 3 in japanese is San and when both 3Q are together they pronounce it as SanQ..
And if you as why is means thank you, this is because they cannot pronounce "Thank" as how english speaker pronounce it and when they try it will sound like San instead of Thank