# Talk

## Maths websites/info/book recommendations needed for Year 5 child

(5 Posts)
tiptop Mon 31-Jan-05 10:28:03

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binkie Mon 31-Jan-05 10:39:49

I looked at your thread because I'd love to find recommendations for good maths websites too (though for Key Stage One more).

Your daughter's doing prime numbers, isn't she?

I did a search for "prime numbers games" and found this bbc website - tell me if it's good!

Beansmum Mon 31-Jan-05 10:53:34

I think you've got the grid thing a bit wrong, you should be crossing out all numbers that aren't prime and leaving the primes. So 2 and 5 shouldn't have been crossed out.

It's called the sieve of Eratosthenes and works like this

1) Write out the numbers from 1 to 100 in ten rows of 10.
2) Cross off number 1, because all primes are greater than 1.
3) Number 2 is a prime, so we can keep it, but we need to cross off the multiples of 2 (all even numbers).
4) Number 3 is also a prime, so again we keep it and cross off the multiples of 3.
5) The next number left is 5 (because four has been crossed off), so we keep it and cross of the multiples of this number.
6) The final number left in the first row is number 7, so cross off its multiples.
7) You have finished. All of the numbers left on your grid are prime numbers.

hope that helps, don't know any websites, sorry.

tiptop Mon 31-Jan-05 11:05:27

binkie - Thanks for the website. I just went on it and scored 4 out of 5 on one game at level one. I had no idea at all of what one question meant, so I took a look at the key and it has a good set of examples there of what's meant by prime numbers, etc. I think both dd and ds would love that website, so thanks again!

Beansmum - I'm going to print off this thread and go through your explanation slowly. I think between your explanation and the games on the website, I'll get the hang of it and then I can help dd. Thanks very much for taking the time to help!

Back to the maths!

tiptop Mon 31-Jan-05 11:26:24

I scored 5 out of 5 at level one on the games section of the website! I'm getting the hang of factors! Now I'm going to try level 2! Dd and ds will love the games on the website. Thanks again, binkie. Once I score well at a higher level, then I'm going to have a go at the grid.

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