Answer
1 picosecond = $\displaystyle \frac{1}{10^{12}}$ seconds.
Work Step by Step
1 hour = 3600 seconds
$3.6\times 10^{15}$ (picoseconds per hour) = $\displaystyle \frac{3.6\times 10^{15}}{1\text{ hour}}\text{ picoseconds}$
= $\displaystyle \frac{3.6\times 10^{15}}{3600 1\text{ seconds}}\text{ picoseconds}$
$=\displaystyle \frac{3.6}{3600}\cdot 10^{15}$ picoseconds per second
$=\displaystyle \frac{1}{1000}\cdot 10^{15}$ picoseconds per second
$=\displaystyle \frac{10^{15}}{10^{3}}$ picoseconds per second
$=10^{15-3}$ picoseconds per second
$=10^{12}$ picoseconds per second
1 picosecond = $\displaystyle \frac{1}{10^{12}}$ seconds.
