Function units 

pub fn units<T: Into<u128>>(n: T, ones: &str, divisor: f64) -> String

Returns an approximate representation of quantity n measured in units ones using prefix notation.

divisor is the prefix value (e.g. 1000 for SI units, 1024 for IEC units).

use jam_tooling::format::units;
assert_eq!("10K", units(10_000_u32, "B", 1000.0));
assert_eq!("2560B", units(2_u32 * 1024 + 512, "B", 1024.0));