Assuming these are all R5, you would need 2900 in order to reach R14 500.
The volume of a R5 coin is a little less than 5000 cubic mm. The volume of a 5L bottle is 5 000 000 cubic mm.
5 000 000/5000 = 1000.
You can only fit 1000 R5 coins in there, not 2900. You have lied, sir