Resources and Tools for Elementary Math Specialists and Teachers
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Clock Arithmetic

This activity and Java applet allows a student to explore modular arithmetic. It is also a tool for finding remainders where all the possible numbers (the numbers less than the divisor) are put in a circle or clock. The learner uses the scroll bar to modify the size of the clock from 2 to 26 hours, sets a starting value and then moves the "clock" forward a number of specified hours to see the resulting sum. Support pages for the learner and the instructor are included.
Contributed by: Shodor, Publisher
Math TopicNumber Sense, Basic Operations, Number Concepts, Algebraic Thinking, Number Theory, Mathematical Practices, Mathematical Processes
Grade Level3, 4, 5
Resource TypeActivity, Interactive Media

  • Additional Information
    • AudienceEducator, Learner
    • LanguageEnglish (USA)
    • Education Topic
    • Interdisciplinary Connection
    • Professional DevelopmentNo
    • ContributorShodor, Publisher
    • Publication Date2005
    • RightsCopyright (c) The Shodor Education Foundation, Inc.
    • AccessFree access
  • Standards
    • Common Core State Standards for Mathematics

      Select a standards document:

  • User Comments
    • 4
      Many uses
      By Uncle Bob on 08/21/2012 - 14:39
    • Although the supporting material is a little light, there are links that take one to deeper discussions. Modular arithmetic has vital applications in cryptology (online commerce, nat'l security). The fact the the 'clock' can go to mod 26 brings many applications into play - base ten, remainders, multiples and division, military time and the alphabet come immediately to mind.