Identifying Prime Numbers PowerPoint

This PowerPoint begins by defining a prime number, then works through eliminating multiples of 2, 3, 5, & 7, using a 1-100 grid. I use the “2 & 3” slides as examples then ask students to eliminate the multiples of 5 & 7 before showing the results for these values which students can then check. Included is a word document of 4 grids (1-100) on A4 for student use. No other eliminations are needed until beyond 100, since all multiples of 11, 13 …. have already been eliminated from this range by earlier multiples, so the list of primes is extended to 25 values, 97 being the highest. A final slide shows the list of primes up to 151.