Fix a test by increasing the precision of output.

Fix a test by increasing the precision of output.

The test outputs 6 digits, so if there is a difference in the 7th digit that
leads to different 6-digit-rounding, then that produces a difference that is
exactly at the numdiff threshold and the test fails.

Fix this by outputting 7 digits. The difference between the current output
and the stored output is then at most one half of the numdiff tolerance,
and the test succeeds.