f65 Factoring Large Numbers- An AskERIC Lesson Plan
Lesson Plan #:AELP-ATH0005

## Factoring Large Numbers

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
411

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
```

May 1994

These lesson plans are the result of the work of the teachers who have attended the Columbia Education Center's Summer Workshop. CEC is a consortium of teacher from 14 western states dedicated to improving the quality of education in the rural, western, United States, and particularly the quality of math and science Education. CEC uses Big Sky Telegraph as the hub of their telecommunications network that allows the participating teachers to stay in contact with their trainers and peers that they have met at the Workshops.

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