Answer: 6
Explanation: Because there is a decimal point, the zero after is included. The first 5 numbers are significant because they aren’t zero. Zeros are included if there is a decimal point (13.0, 160.0) or are in the middle of a number (16007, 101). They are not included if they are before a decimal (000.0081, 0.000021)-(there are only 2 sig figs in these: the actual numbers) or after a number without a decimal (15840000, 100)-(all the zeros in these numbers are not significant).