如何将QTableWidgetItem符号更改为标准符号

I have QTableWidget with 3 columns. I multiply numbers in first and second column and write result in third column. Numbers are double. The problem is: result is in scientific notation like "1.4e+3". How can I change notation to standard notation? I use Qt 4.8 and Ubuntu 12.10.I have QTableWidget with 3 columns. I multiply