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SSC CGL Tier II 25 Oct 2015 Paper 1

Question : 66 of 100

Marks: +1, -0

(2467)^{153} \times (341)^{72}

Solution:

(1)

7^{1}=7,\;7^{2}=49,\;7^{3}=343

7^{4}=2401,\;7^{5}=16807

i.e. after index 4, the unit’s digit is repeated.

∴ On dividing 153 by 4, remainder = 1

∴ Unit’s digit in the expansion of

(2467)^{153} = 7^{1} = 7

and

unit’s digit in the expansion of

(341)^{72} = 1

∴ Required unit’s digit

= 7 \times 1 = 7

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