1.

In the expansion of 311 the units digit is …………….. A) 3 B) 7 C) 10D) 16

Answer»

Correct option is  B) 7

Correct option is (B) 7

\(\because3^4=3^2\times3^2=9\times9=81\)

Unit's digit in \(3^4\) = 1

\(\therefore\) Unit digit's in \(3^{11}=3^4\times3^4\times3^3\)

\(=1\times1\times7=7\)

\((\because\) Unit's digit in \(3^4\) = 1 & unit's digit in \(3^3\) = 7  \((\because3^3=27))\)



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