Answer:
9.89×10^-9
Step-by-step explanation:
0.000 000 009 89 = 9.89×10^-9
__
We have introduced spaces in the number to make the digits easier to count. (Some technical publications will write the number with thin spaces for just that reason.) The most-significant digit is in the 9th place to the right of the decimal point, so has a place value of 10^-9.
