Referring to table 2 of AMS2431/4c
It states that the area of a quarter of an inch squared is 161mm and that one sixteenth of an inch has an area in millimeters of 40mm. Both are wrong and contradicts table 2B of AMS2430 rev.S and the analysis procedure.

Inch mm Area mm
1 25.4 645.16
0.5 12.7 161.29
0.25 6.35 40.3225
0.0625 1.588 2.521744