Is it normal as a 42 yr old woman to find yourself confused and making simple mistakes daily?

No: It is not normal for a person to be confused and making simple mistakes daily, except for maybe the very young and the very old. A person with such symptoms can see a primary care doctor to find out why. Some reasons are lack of sleep, excess stress, being overworked, depression, anxiety, drug/alcohol effects, medicine effects, toxins, hormonal imbalances, early brain (cognitive) changes, etc...

No: If anyone suddenly has a change in how they are functioning, that could be a sign of an underlying problem. I suggest having an examination by a qualified physician and to get this checked out. It could be something easily diagnosed and treated, but something which could worsen without the appropriate attention. As your symptoms could be many things, i choose to not just make guesses.

May be not: New onset of confusion in 42 y old woman is not normal, as this is also common time for onset of menopause, thyroid problems, diabetes, hypertension and depression which may all present this way and hence worth investigating. I would recommend a through physical by primary physician as a start.