automating a function

[val2009]

Struggling to get my head around the following problem...errrh.

I have random numbers in the range "B:Z" and want to create a sweeping effect on the row, by multiplying it by a percentage in "A".

Example, B1 and B2, have the integer "20" and "10" respectively.
A1 is my multiplier and I set that to 50%.

Once I set my multiplier to 50, I'd like to see the changes propogated to these cells, so that B1 and B2 are now 10 and 5 respectively.

Is there a function that could do this automatically within the worksheet, or do I need to write a script?

many thanks!