I am experiencing the same problem in both Excel 2002 and 2003.

The CHITEST worksheet function is "sometimes" returning #NUM! instead of a
number.

CHITEST syntax is CHITEST(actual_range,expected_range)

I am running CHITEST against 6 ranges of numbers - 10,000 numbers in each
range. The expected range is always the same, for all of my CHITEST
instances.

One of the six ranges is returning #NUM!, the other 5 return a number(as I
expect).

I looked up the meaning of #NUM! - one listed cause is that some of the
arguments are not numbers.

I ran the COUNT function against the range - COUNT thinks they are all
numbers.

So, I ran CHITEST on a some sub-ranges of the range where CHITEST returns
#NUM!.

Example:

Range of numbers RESULT

1-10,000 #NUM!

1-30 number
1-100 number
1-1000 number

1-2000 #NUM!

1001-2000 #NUM!

1001-1500 number
1501-2000 number

I am stumped about why CHITEST would return a number for the sub-ranges
1001-1500 AND 1501-2000 but NOT for the sub-range 1001-2000.

What am I missing?