There are 12 balls numbered from 1 to 12. The number of ways in which they can be used to fill 8 places in a row so that the balls are with numbers in ascending or descending order 

12 balls are numbered 1 to 12

No of ways of filling 8 balls in increasing order $={12}_{{\mathrm{C}}_8}$

No of ways of filling 8 balls in decreasing order $={12}_{{\mathrm{C}}_8}$

No of ways in which balls can be arranged in increasing or decreasing order $=2\left({12}_{{\mathrm{C}}_8}\right)$