Solution 1: Suppose that the original number is 100. When 100 is increased by $60\%$, the result is 160. To return to the original value of 100, 160 must be decreased by 60. This percentage is $\frac{60}{160} \times 100\%=\frac{3}{8} \times 100\%=37.5\%$. Solution 2: Suppose that the original number is $x$ for some $x>0$. When $x$ is increased by $60\%$, the result is $1.6x$. To return to the original value of $x$, $1.6x$ must be decreased by $0.6x$. This percentage is $\frac{0.6x}{1.6x} \times 100\%=\frac{3}{8} \times 100\%=37.5\%$.