How many 4 digit numbers with first digit 2 have exactly two identical digits

1) 144
2) 216
3) 288
4) 648
5) 432

• 432
  when other identical digit is also 2, then 9*8= 72 ways to select other 2 different digits .
  These three digits can be arranged in 6 ways.
  so possible numbers = 72*6=432
  when identical digit is not 2.
  Then number of ways to select other 3 digits = 9*8=72
  number of ways to arrange 3 digits = 72*3=216
  
  so total numbers possible = 432+216 = 648
• 11 years agoHelpfull: Yes(0) No(0)