[tacos]

write one? it's simple algebra.

[nitrogen]

The problem is performance when working with an entire object rather than a primitive type.

[acchow]

Your homegrown object wouldn't have any special meaning in the JVM and wouldn't be able to be optimized as a 128-bit integer.

[jovdg]

Parent probably means writing the muldiv function, which would return a "basic" 64bit int.