A research lab in Chennai requires 100 mice and 75 sterilized cages for a certain set of laboratory
experiments . To identify the mice, the lab has prepared labels with numbers 1 to 100 , by combining tags
numbered 0 to 9. The SPCA requires that the tags be madeof toxin-free material and that the temperature of
the cages be maintained at 27 degree Celsius. Also , not more than 2 mice can be caged together and each cage
must be at least 2 sq.ft in area. The 5 experiments tobe conducted by lab are tobe thoroughly documented and
performed only after a round of approval by authorities. The approval procedure takes around 48 hours. How
many times is the tag numbered '4' used by the lab in numbering these mice?
a) 9
b) 19
c) 20
d) 21

• it is 20 ( we should count the digit 2 times in 44)
• 9 years agoHelpfull: Yes(4) No(0)
• its very simple.
  it asked about how many times 4 repeated between 1 and 100.
  so it is 20
  4,14,24,...........,94-10 times 4 appears in unit place
  40,41, .......... 49- 10 times 4 appears in tenth place
  so 10+10=20
  
• 9 years agoHelpfull: Yes(2) No(0)
• ans=19
  no. of 4 appearing in numbers from 1 to 100 is 19.
• 9 years agoHelpfull: Yes(0) No(1)
• answer is 20
  from 1-100 four appeared in 20 times
• 9 years agoHelpfull: Yes(0) No(1)
• 20 according to formula 2b where base =10
• 9 years agoHelpfull: Yes(0) No(0)