This interactive Java applet provides students with practice in subtraction and pattern recognition. Starting with four numbers in the corners of an outside square, students find the differences (larger minus the smaller) between the pair of numbers on each side of the square. After correctly completing each square, they repeat the process for the next inner square, until all squares are complete. Students can explore the patterns that emerge as they work toward the center square. Users can choose to work with whole numbers, integers, fractions, decimals, or money. They may also create their own problems by selecting the four starting numbers for the outside square.


  • Mathematics > General
  • Education > General

Education Levels:

  • Grade 1
  • Grade 2
  • Grade 3
  • Grade 4
  • Grade 5
  • Grade 6
  • Grade 7
  • Grade 8
  • Grade 9
  • Grade 10
  • Grade 11
  • Grade 12


oai:nsdl.org:2200/20140728160934831T,Grade 2,Grade 1,Make use of structure,NSDL,Grade 4,Grade 3,Critical thinking,Early Elementary,Express regularity,Mathematics,Number concepts,Social Sciences,Arithmetic,Analyze and persevere,Fractions,Process skills,Number and operations,Upper Elementary,Grade 5,Subtraction,Patterns and sequences,Informal Education,Integers,Whole numbers,NSDL_SetSpec_ncs-NSDL-COLLECTION-000-003-112-027,Comparison of numbers,Practice Standards,Elementary School,Number patterns,Reason quantitatively,Decimals,Operations,Mental calculation,Money,Engineering,Measurement,Education,Reasoning



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