To express even more big exchange than kSPN, use MSPN. One MSPN is one thousand kSPN. 1kSPN is 1/1000MSPN. MSPN is very suitable for large transaction.
MSPN is different from mSPN that one mSPN is one thousandth of one SPN.
Another case, what about a cup of coffee? It values 1500000 SPN. I want three cups of coffee that for 4500000 SPN. Hmm, I feel a little painful for that long digits, so we will use MSPN for that: a cup of coffee for 1.5 MSPN, three cups of coffee for 4.5 MSPN.
1MSPN = 1000kSPN
1MSPN = 1,000,000SPN
1000MSPN = 1GSPN