The number of spaces that follow an abbr. is one.
no spaces
2
2
1
50 million gazillion
Unlike the period at the end of a sentence (which have one or two spaces), the period following an abbreviation only needs one space. This is the general rule for abbreviations such as Dr., Jr., or Sr.
There aren't any spaces after the apostrophe in a contraction (did you see what I did?)
None!
none
There should be one space.
One space follows a period after an initial.
One space is sufficient.