how many globular clusters are in the milky way
About 150 to 158 currently known
Globular cluster
Globular clusters are fairly common; there are about 150 to 158 currently known globular clusters in the Milky Way, with perhaps 10 to 20 more still undiscovered. 
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Globular cluster [SEP] Introduction
Larger galaxies can have more: The Andromeda Galaxy, for instance, may have as many as 500. Some giant elliptical galaxies (particularly those at the centers of galaxy clusters), such as M87, have as many as 13,000 globular clusters. Every galaxy of sufficient mass in the Local Group has an associated group of globular clusters, and almost every large galaxy surveyed has been found to possess a system of globular clusters. The Sagittarius Dwarf galaxy, and the disputed Canis Major Dwarf galaxy appear to be in the process of donating their associated globular clusters (such as Palomar 12) to the Milky Way.