In the State of Ohio, the Secretary of State certified 7,531,555 votes cast for the electors of a President in 2000. A single vote's influence, then could be expressed as:

1 / 7531555 = 1.327747058874300E-07 according to Microsoft Excel on a Pentium IV.

The Windows XP calculator displayed 1.3305746086447432323648967806747e-6 for the same calculation. Reassuring. My Palm's calculator agrees with Excel.

If one more person had voted, that vote's influence drops to 1.327746882583090E-07, a difference of 1.762912017777380E-14. The single vote's influence drops to 99.99999867225312% of its original influence.

Now, if you bring a person to vote who wasn't going to vote and agrees with you, your influence jumps to 2 / 7531556, or 2.655493765166190E-07, a difference of 1.327746706291890E-07. Dividing the new influence into your original influence, your new influence is 199.9999973445%. I know it's going to shock and amaze you that it's just under two; but this is just a fancy way of saying, "Vote, and take a friend!"