All XL numeric values are doubles.

The problem is inherent in double precision floating point math.

No, I am aware of this problem (which usually only affects the last 2 of 3
decimal digits in a Double)... what happened is I looked at the number
Michele posted and, without counting to see the first non-zero digit was in
the 14th decimal digit, saw half the number was affected by the problem and
thought 8 zeroes followed by 8 garbage digits... it looked like the old
Single-to-Double coercion problem.

Rick