Learn Indonesian Numbers
The Indonesian numbers are very easy to remember. What you need to do is to cite the numbers at random order to make you get used to it. If it is possible you can try to associate the numbers with things such as prices, addresses, sizes, lengths, etc.
For -teens (numbers 13-19, thirteen, fourteen etc), you have belas in Indonesian language. So, for numbers (13-19) you should say 13 (tiga belas), 14 (empat belas), 15 (lima belas), etc. While for -ty (numbers 20-90), you have puluh in Indonesian language. So, for...