Kapusta – “Actually, speaking of Rav Chaim, I think the Rebbitzin a”h worked as a bookkeeper and enjoyed math and on walks (on Shabbos?), Rav Chaim would discuss things which included math.”
Kapusta, that is correct, and according to her biography, there was a particular Tosfos which involved math which he used to discuss with her.
Additionally, she spent several hours learning every day.
It is a Mitzvah for girls to learn if they can and even a chiyuv to learn certain (a lot of) things. According to Rav Avigdor Miller, the difference between men and women is that she has more excuses not to learn. But she should certainly learn as much as she can, and it is definitely praiseworthy.
dovrosenbaum:If she can’t learn because she has to take care of the kids or cook, that is one thing, but it is not a Mitzvah to davka come up with other things to do in order to avoid learning.