Answer:
6.8 times 10 to the -6 power
Explanation:
First you find a number that's between 1 and 9.9. You can't have a number that is 10 or greater, or a number less than 1. You can however, have decimals.
For this problem, you first find that decimal between 1 and 10. In this case, that number is 6.8. Now you figure out what power of 10 you multiply by to get 0.0000068. A trick to find out what power of 10 you use is to count how many spaces the decimal moves to get from the original number to the new number. However many spaces that is, that is your power of ten. To find out whether that number is positive or negative, see if your number gets bigger or smaller when it gets put into scientific notation. If it gets bigger, the power of ten is negative. If the number gets smaller, the power of ten is positive. You can think of this as the negative sign pointing in the direction you are moving the decimal point.
Good Luck!