split --number K/N appears to lose data in, with the sum of the sizes of the output files being smaller than the original input file by 131072 bytes.
$ split --version
split (GNU coreutils) 8.30
...
$ head -c 1000000 < /dev/urandom > test.dat
$ split --number=1/4 test.dat > t1
$ split --number=2/4 test.dat > t2
$ split --number=3/4 test.dat > t3
$ split --number=4/4 test.dat > t4
$ ls -l
-rw-r--r-- 1 user user 250000 Jan 22 18:36 t1
-rw-r--r-- 1 user user 250000 Jan 22 18:36 t2
-rw-r--r-- 1 user user 250000 Jan 22 18:36 t3
-rw-r--r-- 1 user user 118928 Jan 22 18:36 t4
-rw-r--r-- 1 user user 1000000 Jan 22 18:33 test.dat
Surely this should not be the case?
Paul