Police spokesman Lieutenant Colonel Moatshe Ngoepe said the incident happened in February last year.
"On the 13 February 2016, the accused robbed Khomotso Mokgerere, aged 22, of his tablet phone and further stabbed him to death with a knife before disappearing with the tablet. Police located him and found him possession of the deceased's tablet within five days," said Ngoepe.
The court sentenced Mathemane to 20 years for murder and 10 years for armed robbery on Thursday.
Mokgerere was a student at the University of Limpopo in Polokwane.