Move me one place in an invoice and ten pounds becomes a hundred; I look tiny, but I can empty a budget. What am I?

You can count along me, divide me, make me negative, and still never reach my final member. What am I?

A sunflower head, a pine cone spiral and the numbers 1, 1, 2, 3, 5 all point to me. What am I?

I may look awkward as 48 over 64, but the more you break me down by common factors, the clearer I become. What am I?

Ten seconds before midnight I make a room loud; ten seconds before an exam I make it silent. Same numbers, different feeling. What am I?

Lawyers build me, logicians test me, and one weak premise can make me collapse. What am I?

I am first in end, last in place, and appear four times in experience. What am I?

I am not written on a CV; comfort may hide me, pressure reveals me, and repeated choices build me slowly. What am I?

A lawyer builds me with facts, doubt weakens me, and proof can make me strong again. What am I?