How do you tell if a significant figure is absent or present?

I understand the Atlantic-Pacific rule...but how do you know if a number is absent or present? Thank you!How do you tell if a significant figure is absent or present?
if there is a point making the number part decimal then the number is present so you count from the pacific side. the number is absent if it is an integer with no point and then you count from the atlantic side. remember count from the first non-zero number.How do you tell if a significant figure is absent or present?
Well I assume this is a Chemistry question, a SigFIg has many rules





200 %26lt;-- 1 sigfig the 2 zero's arent sigfigs





2001.00004 %26lt;--- this has 9 sig figs because there is a point and because the zeros are between 2 numbers google it foo