CECmath.31


TITLE:    FACTORING LARGE NUMBERS

AUTHOR:   Tim Olson, Meadow Valley Middle School
          Panaca, Nevada

GRADE LEVEL/SUBJECT:  Grade 7,   Math

OVERVIEW:  Know the basic rules for divisibility ie: 2's are
even, 3's add the digits etc.

ACTIVITIES:  Have students choose a large even number, say
642, how could you tell what numbers that are all prime
would go into this number?

Let the students discover how many times they can divide out
a group of small numbers.  Then introduce the tree of
organization to the process.

                 642

                 321*2     2 is prime, circle it.

                 17*3      both are prime, we can stop.

This process can be used for many different things in basic
math skills including, fractions, common denominators, and
decimals but division skills can only be improved by doing
basic practice.

ADDITIONAL ACTIVITIES:  Factor method for large fraction
reduction.

                         884
                         ---
                         1224        884          1224

                                   221* 4       102* 12

                                17*13  2*2    51*2    3*4

                    2*2*13*17

                   2*2*2*3*3*17

          leaving 13\2*3*3=13\18