Patents by Inventor John A. Crowdis

John A. Crowdis has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Patent number: 4903990
    Abstract: A printed sheet of paper that is useful as a self-evaluated mathematics test is disclosed. The sheet has inscribed thereon an arrangement of the numerals that represent first and second cardinal numbers. The numerals are so positioned as to indicate a mathematics problem calling for the first and second numbers to be either added together, subtracted one from the other, multiplied one by the other, or divided one by the other. The correct answer to the problem is a third number having at least two digits, but that number does not appear in the arrangement. Instead, there is the inscription of a fourth number (a "check answer"), which reprsents the sum of all of the digits of the correct answer. The student can check the correctness of his or her answer before handing in the completed test, by adding together the digits in his or her answer and seeing if the sum matches the check answer. If the two do not match, the student knows to rework the problem, but still does not know what the correct answer is.
    Type: Grant
    Filed: April 26, 1989
    Date of Patent: February 27, 1990
    Inventor: John A. Crowdis