If there are approximately 7.9 million species on Earth and about 15% of them are mammals, how many mammal species are there?
To find out how many mammal species there are, we need to calculate 15% of the total number of species (7.9 million).

To do this, multiply the total number of species by the percentage (as a decimal):

Number of mammal species = Total species × Percentage
                                     = 7,900,000 × 0.15

Number of mammal species = 1,185,000

So, there are approximately 1,185,000 mammal species on Earth.