What is the number of ways in which the letters of the word 'ABLE'...

2nd and 4th place are even place, so vowel ' $A$ ' and ' $E$ ' arrange either 2 nd or 4 th place in $2!=2 \times 1=2$ ways Consonent letter, ' $B$ ' and ' $L$ ' arrange at 1 st and 3rd place in $2!=2 \times 1=2$ ways. Total number of arrangement $=2 \times 2=4$.