What is the current zakat nisab in Saudi Riyals, how can zakat be calculated on a monthly salary that sometimes falls below the nisab, and is giving money to a needy grandmother for medication considered part of zakat?

The zakat threshold for paper currency is the equivalent of 85 grams of gold or 595 grams of silver. If a person possesses this amount and it remains with him for a full lunar year, zakat becomes obligatory on it at a rate of 2.5%. What is given to a grandmother to buy medicine is not counted as zakat. If she is capable, she is not among those eligible for zakat. If she is not capable, then she is poor, and her financial support becomes obligatory upon her capable children and grandchildren.