The lower portion of an income statement for McDonald’s follows (dollars in millions):
Income from continuing operations ...............................................$2,873.0
Income from discontinued operations net of taxes ............................671.2
Net income ...................................................................................$3,544.2
Basic net earnings per share:
Continuing operations ......................................................................$ 2.33
Discontinued operations .....................................................................0.54
..........................................................................................................$ 2.87
Diluted net earnings per share:
Continuing operations ......................................................................$ 2.30
Discontinued operations .....................................................................0.53
..........................................................................................................$ 2.83

REQUIRED:
a. Why is there a distinction between net earnings from continuing operations and net earnings from discontinued operations?
b. Estimate the number of common shares outstanding.
c. Why is there a distinction between basic net earnings per share and diluted net earnings per share?
d. Estimate the number of common shares that would be outstanding if all potentially dilutive securities were converted to common shares.