The 4-digit numbers can be formed from digits 1 to 5 in $\,{}^5 P_4$ ways. ∴ The required 4 digit numbers = $\,{}^5 P_4$ = 120 For 4-digit even numbers unit place can be filled by 2, 4, i.e., in 2 ways. Then the remaining three places can be filled in $\,{}^4 P_3$ ways. ∴ The required 4-digit even numbers = 2 × $\,{}^4 P_3$ = 2 × 24 = 48