How many significant figures are in 0.7?

Answer 1

0.7 has one significant figure.

Any non-zero digit is significant (165 has three significant figures).

Any zero between non-zero digits is significant (304 has three significant figures).

Any zero to the right of a non-zero digit in a number which includes a decimal point is significant (10,000 has one significant figure, .0001 has one significant figure, but 100.0 has four significant figures, as does 0.001000).

In this case, only the 7 is significant.