This puzzle asks you to make as many of the numbers from 1 to 100 as you can by multiplying other numbers together. The catch is there are rules about the numbers you can use! The aim is to investigate the prime numbers and a little bit about their role in our number system! Please find the worksheet attached below. You can print it or do it straight on your computer.

Time 1hr

Age 11+

Why we like this activity....

Prime number decomposition can often seem to be without a point. Looking at it this way, by starting with a
challenge invites to student to think about the patterns they observe and notice the powerful fact that all numbers can
be expressed as producs of prime numbers. The activity engaes first then delivers! Its also graet mental arithmetic
practise and has that little edge of competetion that can be fun.

How this activity can be used....

On paper on computer, individually or in groups, there are lots of options. I start with individuals and encourage
pairing up and grouping as we go through so that students can pool resources and share their observations.

What to expect when using this activity, from our experience...

A good buzz and lots of hypothesizing! Students need eachother to point out when non primes have inadvertently
been used.

Extra notes

See other activities on prime numbers, Investigation and Prime number murder mystery

 

Author/Date Jim Noble, 13/09/09