In Atlantis you can perform calculations directly in the document window. For this type the required arithmetic expression in the document, select this expression, then press the Alt+= keys or click the Calculate
toolbar button. If your expression is OK, Atlantis would place the computed result onto the clipboard so that you could paste it to this or any other document.
Your expressions for calculation could include integer numbers as well as real numbers both in floating point notation and scientific notation. For example: