“Fully insured individual” defined
The term “fully insured individual” means any individual who had not less than—
(1)
(1)#
one quarter of coverage (whenever acquired) for each calendar year elapsing after 1950 (or, if later, the year in which he attained age 21) and before the year in which he died or (if earlier) the year in which he attained age 62, except that in no case shall an individual be a fully insured individual unless he has at least 6 quarters of coverage; or
(2)#
40 quarters of coverage; or
(3)#
in the case of an individual who died before 1951, 6 quarters of coverage;