Hello thanks for reporting the problem.
The cause of this problem is that the XP formula is partially omitted.
days studied percentage :
As you said this is calculated at 100.
Retention :
Retention is bonus is added, so it will be a little larger than the actual value.
(e.g. 70% → 85%, 40% → 55% )
Retention Bonus:
85%-100% -> 100%
70%-84% -> 85%
55%-69% -> 70%
40%-54% -> 55%
25%-39% -> 40%
10%-24% -> 25%
0%-9% -> 0%
If you want to do the calculations in Excel, try this. (Use 100 for Retention, not 100%. It will be % after calculation.)
=IF(F8 >= 85, 1, IF(F8 >= 70, 0.85, IF(F8 >= 55, 0.70, IF(F8 >= 40, 0.55, IF(F8 >= 25, 0.40, IF(F8 >= 10, 0.25, 0))))))