The following general rules for determining the number of significant figures in a number can help to solve problems with ambiguities in significant figures:

A) All non-zero numbers are significant.  

B) All zeros between significant numbers are significant, for example the number 1002  has 4 significant figures.

C) A zero after the decimal point is significant when bounded by significant figures to the left, for example the number 1002.0  has 5 significant figures.

D) Zeros to the left of a significant figure and not bounded to the left by another significant figure are not significant. For example the number 0.01 only has one significant figure.

E) Numbers ending with zero(s) written without a decimal place posses an inherent ambiguity. To remove the ambiguity write the number in scientific notation. For example the number 1600000 is ambiguous as to the number of significant figures it contains, the same number written 1.600 X 10⁶ obviously has four significant figures.