Abstract: The present invention generally relates to a writing instrument that includes a means for calculating the result of specific a non-linear equation, such as the Body Mass Index (BMI) of a person or the energy developed by a falling object. The present invention is a writing instrument which combines a writing instrument with a calculating device in one lightweight and commonly used type of device, thereby freeing the user of the need to refer to complicated charts or other technical materials. The writing implement has a first end which includes the writing tip portion and a second end which includes the tables and operational elements used to calculate a particular formula based on user specified numerical values.