Bunuel wrote:
What is the units digit of \(4^{93}*9^{15}*3^{81}*7^{56}*2^9\) ?
A. 0
B. 1
C. 4
D. 5
E. 6
\(4^{93}*9^{15}*3^{81}*7^{56}*2^9\)
=\(2^{186}*3^{30}*3^{81}*7^{56}*2^9\)
=\(2^{195}*3^{111}*7^{56}\)
Now,\(2^{195} = 2^{4*48+3}\) ; So this will have units digit8
\(3^{111} = 3^ {4*36 + 3}\) will have units digit as 7
\(7^{56} = 7^{4*24}\) will have units digit as 1
Finally we have units digit as 8*7*1 = xx56 , thus Answer must be (E) 6
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