Scientists have long suspected that monkeys are capable of mental arithmetics and a new study is helping them prove it. A research team led by neurobiologist Margaret Livingstone trained three rhesus macaques to identify symbols representing the numbers zero to 25. They then taught the test subjects how to perform addition. To eliminate the possibility of rote learning, the team had the monkeys learn an entirely different set of symbols representing the numbers zero to 25. The monkeys were able to reapply their previous knowledge to the new set and continue performing basic mathematics.