Abstract: A calculator is adapted to be releasably attached to a conventional tape rule. A calculator case is attached to the rule with a flat rubber band that sits in a recessed channel in the case and passes around the tape rule. Alternatively the case may be attached to the tape rule with the screw that usually attaches a belt clip to the rule. The calculator is snapped into a protective pocket in the case. The calculator may be oriented face down so that the back of the calculator protects the keypad and display, or face up to expose the keys and display for use. The calculator may also be oriented in either of two positions differing by 180 degrees about an axis perpendicular to the case. Or the calculator may be removed from the case for independent use. Using the tape rule/calculator combination, a user may measure a distance and enter it into the calculator without releasing the tape rule.

Abstract: A portable hand-held electronic calculator for performing feet, inch, and fraction calculations and for displaying numerical results in feet, inches, and fractions of inches. Values for feet, inches, and fractions of inches can be entered directly without first changing the numbers into a decimal format and complex calculations, such as multiplication, division, addition, subtraction, squares and square roots can be performed directly. A specialized sequential display allows the user to manually enter numeral data in a particular sequence related specifically to the sequence that feet, inches, and fractions are conventionally written and spoken in the construction industry.