Six identical cards are placed on a table. Each
card has number '1' marked on one side and
number '2' marked on its other side. All the
six cards are placed in such a manner that the
number '1' is on the upper side. In one try,
exactly four (neither more nor less) cards are
turned upside down. In how many least
number of tries can the cards be turned
upside down such that all the six cards show
number '2'on the upper side ?
(a) 3
(b) 5
(c) 7
(d) This cannot be achieved

• initial 111111
  step1 222211
  step2 211121
  step3 222222
  so ans is 3
• 10 years agoHelpfull: Yes(1) No(0)
• (a) 3
  
  111111
  step 1. 222211
  step 2. 211121( you can chose any 4 cards so select 3 2s and 1 1.)
  step 3. 222222
• 10 years agoHelpfull: Yes(0) No(0)
• least no of tries are as follows such that number "2" on upper side
  111111(initially)
  222211
  211121
  222222
  after 3rd try all cards are having number "2" on upper side
• 9 years agoHelpfull: Yes(0) No(0)
• initially thety all already in a 111111
  so they turned all the 6 at a one time it becames 222211
  rest is two digits diff compare to all
  first time wen turned 222211
  second time wen turned 222221
  thirt time wen turned 222222
• 6 years agoHelpfull: Yes(0) No(0)