Do you really have to do a search for numbers greater than the sqrt(N)?

You right. And now you pointed it out, it seems fairly obvious:

3600: sqrt=60; 59* 61= 3599

10000: sqrt=100; 99*101= 9999

12: sqrt=3.464; 3* 4= 12

Which, in very non-technical terms because my memory doesn't go back to my formal math days, says to me that:

with lo = int( sqrt( N ) ) & hi = int( sqrt( n ) )+1; lo * hi is always less than or equal to N.

If you reduce lo, leaving hi the same, you get further away from N. And if you increase hi, lo will be nearer.

Does that form an explaination? Hmm. Maybe one of our resident math whiz can phrase that correctly?

Examine what is said, not who speaks.
Silence betokens consent.
Love the truth but pardon error.

In reply to Re^3: OT: Finding Factor Closest To Square Root by BrowserUk
in thread OT: Finding Factor Closest To Square Root by QM

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