- simply open any of your txt files or use an empty new one. Enter 2 plus 3 and press Enter. The result " = 5 " will be added automatically - use any of +, -, /, * operations or math functions (sin, asin, sinh, exp, sqrt, log etc) - change any of entered numbers and the whole content will be recalculated according your changes. - save the document as a txt file or print out it as usual. Use it later again - open many files together