Recuring seach and replace with a twist.

Hi,

If I have a text with something like...

"A=1 A=2 A=3 A=4"

I want to replace all the instance of "A=num" with "B=num*num", (the square
root of the number after A)

So that in the example above

"A=1 A=2 A=3 A=4"
Would become
"B=1 B=4 B=9 B=16"

If I run a simple recurring update it does not work.

UPDATE tableA SET contentA = REPLACE (
contentA,
'A=',
'B=' );

Would of course only replace 'A=' and give me:

"B=1 B=2 B=3 B=4"

So, how can I do a recurring search and replace the value and the text after
what I am searching for?

many thanks

Simon