Given a size, S, that is some multiple of P=4096; and record size R; find the largest common multiple of R & P < S.

Eg. S = 2GB = 2147483648; R = 12; LCM of 12 & 4096 < 2147483648 = 2147475456.

Easy to find iteratively:

$R = 12; 
$S = 2*1024**3; 
$c -= 4096 while $c % $r; 

print $c;;
2147475456

[download]

But it can be calculated right? (Long day; brain not cooperating.)

Note: P is always 4096; R can be larger or smaller than 4096; S will always be a multiple of P, and usually a multiple of 1GB.

Eg2. S = 3GB = 3221225472; R = 5007; LCM of 5007 & 4096 < 3221225472 = 3219861504.

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In reply to Simple arithmetic? by BrowserUk

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