If she reached the age of puberty when she was 15, this means that she had fasted 30 Ramadan’s and probably missed 7 days each due to menses. This
makes it 210 days.

If she fasts every Monday, Thursday and 3 white days of ever month this is an average of 110 days every year. She can make up these missed days in two years only

There’s a lady of age 45 who didn’t know that a woman has to make up her missed fasts. She got to know for the very first time at this age. Now what’s the ruling regarding her missed fasts which would be around 400_450. What if she can’t afford to give kaffara as well?

Fasting |