Q. How many 2 digit numbers are there which have 8 as the unit number in it's square.

Option
a) 3
b) None
c) 2
d) 1

• none
  as no number has 8 in ubit number in its square.
• 12 years agoHelpfull: Yes(5) No(0)
• 1^2=1
  2^2=4
  3^2=9
  4^2=16
  5^2=25
  6^2=36
  7^2=49
  8^2=64
  9^2=81
  
  no square ends with 8 ,so none
  
  ans: (b)
• 9 years agoHelpfull: Yes(1) No(0)
• As no 1 digit number has 8 as unit number in its square.
  So no 2 digit number can have 8 as the unit number in it's square.
  
• 12 years agoHelpfull: Yes(0) No(0)
• Answer is : b) None
  
  Square numbers are formed by multiplying a number by itself and in the process, unit digit of the number gets multiplied by itself to give the unit digit of the square number,
  
  We can observe that :
  Unit digit 1 to power of unit digit 1 is 1 (Example of the kind : 21 to power of 21 = 441, which gives unit digit to be 1) ,
  Unit digit 2 to power of unit digit 2 is 4,
  Unit digit 3 to power of unit digit 3 is 9,
  Unit digit 4 to power of unit digit 4 is 6,
  Unit digit 5 to power of unit digit 5 is 5,
  Unit digit 6 to power of unit digit 6 is 6,
  Unit digit 7 to power of unit digit 7 is 9,
  Unit digit 8 to power of unit digit 8 is 4,
  Unit digit 9 to power of unit digit 9 is 1,
  Unit digit 0 to power of unit digit 0 is 0
  
  And it is clear from above, that no square number is having 8 at its unit digit. So none will have 8 as the unit number in it's square.
• 7 years agoHelpfull: Yes(0) No(0)