Write   68%     0.64     13/20       in ascending order of size
68%
0.64
-----  = 64%
100
13    100
--- / ----  = 20 divide into  100 = 5 x 13 =65%
20      1
 
answer   0.64,  13/20,   68%  
which is closest to size 2/3     answer 64%