Thread: Please help us answer this 11+ question

Hi, .
Please see below a question on my 11 year old daughter's exam paper that we have no idea of the answer.

Find two numbers which when multiplied together make a thousand. neither of the two numbers must use any zeros.

Then, find two numbers which when multiplied together make a million. again neither of the two numbers must use any zeros.

Is there a quick way to do this rather then guess numbers a multiply them?

Thanks
Alvina

Originally Posted by dee@landspace.co.uk

Hi, .
Please see below a question on my 11 year old daughter's exam paper that we have no idea of the answer.

Find two numbers which when multiplied together make a thousand. neither of the two numbers must use any zeros.

Then, find two numbers which when multiplied together make a million. again neither of the two numbers must use any zeros.

Is there a quick way to do this rather then guess numbers a multiply them?

Thanks
Alvina

If you look at all the factor of 1000



then pick three and three such that the product of each have no zeros. The same goes for the next problem.

Dear dee@landspace.co.uk,

I suppose that we talk about positive integer numbers.
Divide up 1000 into prime numbers:
1000 = 10*10*10 = 2*2*2*5*5*5.
We have to componate two groups so that the two numbers have not any zeros. Zero will appear if the number containts 2 and 5 together. Therefore the one number = 2*2*2 the other = 5*5*5.

Thank you very much indeed for solving this question . you made it look really easy. Thanks

Deee