Question

How many significant figures are there in each of the following measurements

23
1.498
283.3
9.855
76.414
32.8
107
0.238
8.0335
0.05587
307
1.40082
0.00058900
4500
350000
180.0

Answer 1

These rules may help:

Leading zeros are not significant. (ie, 0.238 has 3 sig figs, not 4; 0.05587 has 4 sig figs, not 5 or 6).

Imbedded zeros are always significant. (ie, 107 has 3 sig figs, or 8.0335 has 5)

Trailing zeros are significant only if the decimal point is specified. Or in lamens terms, if there is a decimal at the end with zeros after (or nothing after) it, all the numbers are sig figs.
Examples:
300 has 1 sig fig (no decimal)
300. has 3 sig figs (decimal makes the zeros important/significant)
300.0 has 4 sig figs (zero after the decimal is also significant)

Good luck :)