QLineEdit and select

[GuL]

I'm using this code

QSqlQuery query_p_total;
 
		query_p_total.prepare("SELECT :x * :y");
 
		query_p_total.bindValue(":x", ui.peso_por_peca_label->text() );
		query_p_total.bindValue(":y", ui.n_pecas_final_lineEdit->text() );
 
		if (!query_p_total.exec()){
			QMessageBox::critical(0, tr("Error"), 
			QString("There is an error with query.exec()!"));
		}else{
			while (query_p_total.next()) {
			ui.peso_total_final_label->setText(query_p_total.value(0).toString());	
			}
		}

QSqlQuery query_p_total;
		
		query_p_total.prepare("SELECT :x * :y");
				
		query_p_total.bindValue(":x", ui.peso_por_peca_label->text() );
		query_p_total.bindValue(":y", ui.n_pecas_final_lineEdit->text() );
		
		if (!query_p_total.exec()){
			QMessageBox::critical(0, tr("Error"), 
			QString("There is an error with query.exec()!"));
		}else{
			while (query_p_total.next()) {
			ui.peso_total_final_label->setText(query_p_total.value(0).toString());	
			}
		}

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ui.peso_por_peca_label->text() ) has value 20.16 and ui.n_pecas_final_lineEdit->text() has value 6, then ui.peso_total_final_label should show me 120.96, but it is showing me 121. When I try to select 20.16 * 6 in the MYSQL console I get the right result, so I think there is something with QLineEdit, but what could it be? Or what else could it be?

Renan