Answer
a) 4
b) 4
c) 6
d) 5
Work Step by Step
a) 0.001125 has 4 significant figures because the zero's before the numbers are insignificant and only 1125 are significant digits.
b) 0.1125 has 4 significant figures because the zero before the decimal is insignificant and only 1125 are significant digits.
c) $1.112500\times10^{4}$ has six significant figures (i.e. all of the numbers are significant) since the zeros are after the decimal place.
d) 11205 has 5 significant figures since it's a whole number and every digit is significant.