Are gold, silver, and currency added together to complete the minimum taxable amount (nisab), and is zakat obligatory by combining them, or is the nisab of each calculated separately?

In conclusion, scholars differed on combining gold with silver to complete the nisab. The majority view is that they should be combined, while the Shafi'is do not hold this view, because each is an independent category. This latter opinion is the more probable one due to the evidence they cited from the Qur’an and Sunnah. As for currency, it must be combined with gold or silver to complete the nisab if the currency alone does not reach the nisab and the owner possesses gold or silver that would complete the nisab with it.