content: <PAGE>
  
                        SECURITIES AND EXCHANGE COMMISSION
                              Washington, D.C. 20549
  
                                     Form 8-K
  
                 Current Report Pursuant to Section 13 or 15(d) of
                        The Securities Exchange Act of 1934
  
                                 September 5, 2000
  
                 Date of Report (Date of earliest event reported)
  
                           Numerical Technologies, Inc.
              (Exact name of registrant as specified in its charter)
  
  <TABLE>
  <S>                                  <C>                          <C>
             Delaware                        000-30005                  94-3232104
  -------------------------------      ------------------------     -------------------
  (State or other jurisdiction of      (Commission File Number)      (I.R.S. Employer
          incorporation)                                            Identification No.)
  </TABLE>
  
                               70 W. Plumeria Drive
                            San Jose, California 95134
                     (Address of principal executive offices)
  
                                  (408) 919-1910
                (Registrant's telephone number, including area code
  <PAGE>
  
  Item 2.
  
       On September 5, 2000, Numerical Technologies, Inc., a Delaware corporation
  ("Numerical"), Numerical Nova Scotia Company, a Nova Scotia unlimited liability
  company and wholly owned subsidiary of Numerical ("Numerical ULC"), Numerical
  Acquisition Limited, a Nova Scotia limited liability company and wholly owned
  subsidiary of Numerical ULC ("Amalgamation Sub"), 3047725 Nova Scotia Limited
  ("ML Holdco"), Cadabra Design Automation Inc., a Nova Scotia limited liability
  company ("Cadabra"), Martin Lefebvre, an individual, and Faysal Sohail, an
  individual, entered into an Agreement and Plan of Amalgamation (the
  "Amalgamation Agreement"). Pursuant to the Amalgamation Agreement, Cadabra, ML
  Holdco and Amalgamation Sub will be amalgamated (the "Amalgamation") to form a
  new Nova Scotia company ("Amalco") and the separate corporate existence of
  Cadabra, ML Holdco and Amalgamation Sub will cease to exist. The Amalgamation
  will result in Amalco becoming an indirect subsidiary of Numerical.
  
       Under the Amalgamation, each Cadabra Common Share, Series A Preference
  Share and Series B Preference Share (collectively, the "Cadabra Capital Stock")
  will be exchanged for 0.1745 Class A Shares of Amalco which will, as soon as
  practicable after the Amalgamation, be reorganized and exchanged for
  exchangeable shares of Amalco (the "Exchangeable Shares") which can generally be
  exchanged for shares of Numerical Common Stock. The Exchangeable Shares will be
  issued by Amalco and, as nearly as practicable, will be the economic equivalent
  of Numerical Common Stock. The Exchangeable Shares will generally be
  exchangeable into Numerical Common Stock at the option of the holder, on a one-
  for-one basis.
  
       In connection with the Amalgamation, approximately 76% of the holders of
  the outstanding Cadabra Capital Stock have entered into voting agreements
  whereby such holders have agreed to vote in favor of the Amalgamation, the
  Amalgamation Agreement and the transactions contemplated therein. The
  Amalgamation is subject to customary closing conditions and is scheduled to
  close by October 1, 2000.
  
       A copy of the Amalgamation Agreement is attached hereto as Exhibit 2.1 and
  incorporated herein by reference in its entirety.
  
  Item 7.   Financial Statements and Exhibits.
  
            (a)  Financial Statements of Business Acquired. To be filed as soon as
                 practicable.
  
            (b)  Pro Forma Financial Information. To be filed as soon as
                 practicable.
  
            (c)  Exhibits
  
  
            Exhibit Number      Description
            --------------      -----------
  
            2.1                 Agreement and Plan of Amalgamation, dated as of
                                September 5, 2000, by and among Numerical
                                Technologies, Inc., Numerical Nova Scotia Company,
                                Numerical Acquisition Limited, 3047725 Nova Scotia
                                Limited, Cadabra Design Automation Inc., Martin
                                Lefebvre, and Faysal Sohail.
  
            99.1                Press Release dated as of September 5, 2000.
  <PAGE>
  
                                    SIGNATURES
  
  Pursuant to the requirements of the Securities Exchange Act of 1934, the
  Registrant has duly caused this report to be signed on its behalf by the
  undersigned hereunto duly authorized.
  
                                              NUMERICAL TECHNOLOGIES, INC.
  
  Dated: September 15, 2000
  
                                              By: /s/ Yagyensh C. Pati
                                                  --------------------------------
                                                  Yagyensh C. Pati
                                                  President and
                                                  Chief Executive Officer
  <PAGE>
  
                                   EXHIBIT INDEX
  
         Exhibit Number          Description
         --------------          -----------
  
         2.1                     Agreement and Plan of Amalgamation, dated as of
                                 September 5, 2000, by and among Numerical
                                 Technologies, Inc., Numerical Nova Scotia
                                 Company, Numerical Acquisition Limited, 3047725
                                 Nova Scotia Limited, Cadabra Design Automation
                                 Inc., Martin Lefebvre, and Faysal Sohail.
  
         99.1                    Press Release dated as of September 5, 2000.
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text: SECURITIES AND EXCHANGE COMMISSION
                              Washington, D.C. 20549
  
                                     Form 8-K
  
                 Current Report Pursuant to Section 13 or 15(d) of
                        The Securities Exchange Act of 1934
  
                                 September 5, 2000
  
                 Date of Report (Date of earliest event reported)
  
                           Numerical Technologies, Inc.
              (Exact name of registrant as specified in its charter)
  Delaware                        000-30005                  94-3232104
  -------------------------------      ------------------------     -------------------
  (State or other jurisdiction of      (Commission File Number)      (I.R.S. Employer
          incorporation)                                            Identification No.)
  70 W. Plumeria Drive
                            San Jose, California 95134
                     (Address of principal executive offices)
  
                                  (408) 919-1910
                (Registrant's telephone number, including area code
  Item 2.
  
       On September 5, 2000, Numerical Technologies, Inc., a Delaware corporation
  ("Numerical"), Numerical Nova Scotia Company, a Nova Scotia unlimited liability
  company and wholly owned subsidiary of Numerical ("Numerical ULC"), Numerical
  Acquisition Limited, a Nova Scotia limited liability company and wholly owned
  subsidiary of Numerical ULC ("Amalgamation Sub"), 3047725 Nova Scotia Limited
  ("ML Holdco"), Cadabra Design Automation Inc., a Nova Scotia limited liability
  company ("Cadabra"), Martin Lefebvre, an individual, and Faysal Sohail, an
  individual, entered into an Agreement and Plan of Amalgamation (the
  "Amalgamation Agreement"). Pursuant to the Amalgamation Agreement, Cadabra, ML
  Holdco and Amalgamation Sub will be amalgamated (the "Amalgamation") to form a
  new Nova Scotia company ("Amalco") and the separate corporate existence of
  Cadabra, ML Holdco and Amalgamation Sub will cease to exist. The Amalgamation
  will result in Amalco becoming an indirect subsidiary of Numerical.
  
       Under the Amalgamation, each Cadabra Common Share, Series A Preference
  Share and Series B Preference Share (collectively, the "Cadabra Capital Stock")
  will be exchanged for 0.1745 Class A Shares of Amalco which will, as soon as
  practicable after the Amalgamation, be reorganized and exchanged for
  exchangeable shares of Amalco (the "Exchangeable Shares") which can generally be
  exchanged for shares of Numerical Common Stock. The Exchangeable Shares will be
  issued by Amalco and, as nearly as practicable, will be the economic equivalent
  of Numerical Common Stock. The Exchangeable Shares will generally be
  exchangeable into Numerical Common Stock at the option of the holder, on a one-
  for-one basis.
  
       In connection with the Amalgamation, approximately 76% of the holders of
  the outstanding Cadabra Capital Stock have entered into voting agreements
  whereby such holders have agreed to vote in favor of the Amalgamation, the
  Amalgamation Agreement and the transactions contemplated therein. The
  Amalgamation is subject to customary closing conditions and is scheduled to
  close by October 1, 2000.
  
       A copy of the Amalgamation Agreement is attached hereto as Exhibit 2.1 and
  incorporated herein by reference in its entirety.
  
  Item 7.   Financial Statements and Exhibits.
  
            (a)  Financial Statements of Business Acquired. To be filed as soon as
                 practicable.
  
            (b)  Pro Forma Financial Information. To be filed as soon as
                 practicable.
  
            (c)  Exhibits
  
            Exhibit Number      Description
            --------------      -----------
  
            2.1                 Agreement and Plan of Amalgamation, dated as of
                                September 5, 2000, by and among Numerical
                                Technologies, Inc., Numerical Nova Scotia Company,
                                Numerical Acquisition Limited, 3047725 Nova Scotia
                                Limited, Cadabra Design Automation Inc., Martin
                                Lefebvre, and Faysal Sohail.
  
            99.1                Press Release dated as of September 5, 2000.
  SIGNATURES
  
  Pursuant to the requirements of the Securities Exchange Act of 1934, the
  Registrant has duly caused this report to be signed on its behalf by the
  undersigned hereunto duly authorized.
  
                                              NUMERICAL TECHNOLOGIES, INC.
  
  Dated: September 15, 2000
  
                                              By: /s/ Yagyensh C. Pati
                                                  --------------------------------
                                                  Yagyensh C. Pati
                                                  President and
                                                  Chief Executive Officer
  EXHIBIT INDEX
  
         Exhibit Number          Description
         --------------          -----------
  
         2.1                     Agreement and Plan of Amalgamation, dated as of
                                 September 5, 2000, by and among Numerical
                                 Technologies, Inc., Numerical Nova Scotia
                                 Company, Numerical Acquisition Limited, 3047725
                                 Nova Scotia Limited, Cadabra Design Automation
                                 Inc., Martin Lefebvre, and Faysal Sohail.
  
         99.1                    Press Release dated as of September 5, 2000.