KayJay: Why use an array? If you do not have a lot of memory, you might have a problem finding the square root of a really large number like one billion.

Iterating until an exact match is overkill. If two successive values match in the first 6-7 digits, you have about 12 or more correct digits.

Can you Redim an array with a Double, which might not be an integer? Does this program compile?

BTW: Can your program find the square root of two or three? It seems to me that you would only iterate once or twice.