> If I am owed 2.575% on $3425956.57 for 245 months, why not get the correct sum Explosion of storage space and computation complexity. When you combine real-w

> If I am owed 2.575% on $3425956.57 for 245 months, why not get the correct sum Explosion of storage space and computation complexity. When you combine real-world numbers with compound interest, every time you add the interest, you’re adding decimal digits to the value. For your example, after 245 months of compound interest at 2.575% per month, the value will have 1228 decimal digits in it, that’s more than 512 bytes to store and process. Another reason is, for the last ~700 years, finance folks use this: https://en.wikipedia.org/wiki/Double-entry_bookkeeping_system https://en.wikipedia.org/wiki/Double-entry_bookkeeping_syste... With that system, coins allow for some kind of rolling checksum verification. BTW, in modern software, the coin is often $/€/whatever 0.0001.