internal/arith: reduce number of concurrent goroutines so we don't have issues with memory usage on travis ci
internal/arith: reduce number of concurrent goroutines so we don't have
issues with memory usage on travis ci


Former-commit-id: e2d9d2b6bd9691ffa3a37f67bf3e33fec6ea16ad [formerly 7232f063c6ee4c81ab7ff41a3c48a5c713ec226d]
Former-commit-id: 736742e0db2c9d80a75f847bb4c158bae3e6e022
EricLagergren/decimal