I guess these are ceramic capacitors.
224 mean 22 x(10 to power 4) in Picofarad (pF) = 220000pF = 220nF. Or 0.22µF.
I.e. the '4' means the number of trailing zeroes.
Don't know where you 'looked up' the 1nF (1000puff as known in the trade!😮)
The leading 2s must appear in the final value!
Thus 1nF would be marked 102 and 10nF 103.
47nF should be marked 473.
After the value code there is usually letter indicating the value tolerance; J, K or M indicating ±5%, ±10% and ±20% respectively.
So, to finally answer your question 🙄; I would use the 47nF capacitors. (=0.047µF)
Older ones may be marked .047.