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Units degit

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Units degit

by maria » Tue May 20, 2008 1:23 pm
x, y, z are consecutive positive integers such that x< y< z. If the units digit of x2 is 6 and the units of y2 is 9, what is the units digit of z2?
A. 0
B. 1
C. 2
D. 4
E. 5

Pls help me. Million thanks.

what is the units digit????
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by punit.kaur.mba » Tue May 20, 2008 1:34 pm
According to me,

Ans = 4.

Explaination:-

If units digit of x^2 = 6. It means x's units digit has to be 6.

For Numbers having units digit as 6 , their squares units digit will be 6. (becos 6 ^ 2 = 36)

Similarly if units digit of y^2 = 9, means y's units digit is either 3 or 7, since square of both will give a 9 in units place.

Since x and y are consecutive y's units digit should be 7.

Hence z's units digit should be 8.

square of a number whose units digit is 8, should have its units digit as 4, since 8 ^2 = 64

Whats the official Ans?
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by maria » Tue May 20, 2008 1:59 pm
punit.kaur.mba,
you are correct. I got it now. Thanks
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