Quoting from here ,
Modern scholarship is agreed on dates in the 8th century C.E., though
it has proved impossible to reach agreement on Shankara’s precise
dates of birth or death. Some religious groups, however, ascribe
B.C.E. dates to him. If these dates were true, then much of what is
claimed about his activities, especially his debates with Buddhists
and Jains, is thrown into doubt.
Of the major Shankara Mathams active today, the Kanchi, Dwaraka, and
Puri ascribe the dates 509–477 B.C.E. to Shankara. The Sringeri
Peetham, on the other hand, accepts the 788–820 C.E. dates.
.....Even though he lived for only thirty-two years, his impact on India
and on Hinduism cannot be stressed enough, as he countered the
increasing sacerdotalism (the belief that priests can mediate between
humans and god) of the masses, and reintroduced a purer form of Vedic
According to wiki too he died at the age of 32.
So,20 years more will be the answer to your question.