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Find unit digit of product (173)45 × (152)77 × (777)999.

A. 4

B. 2

C. 8

D. 6

E. None of these

Answer: Option C

Solution(By Examveda Team)

To find unit digit of a number or an Expression, We have to divide the number or expression by 10 and the remainder obtained by this operation would be the required unit digit.
$$\eqalign{ & \frac{{ {{{\left( {173} \right)}^{45}} \times {{\left( {152} \right)}^{77}} \times {{\left( {777} \right)}^{999}}} }}{{10}} \cr & {\text{Remainder}}\,{\text{would}}\,{\text{be}}\,{\text{same}}\,{\text{as}}, \cr & \frac{{ {{3^{45}} \times {2^{77}} \times {7^{999}}} }}{{10}} \cr & Or,\,\frac{{ {3 \times 2 \times {7^3}} }}{{10}} \cr & Or,\,\frac{{ {6 \times 343} }}{{10}} \cr & {\text{Remainder}}\,{\text{would}}\,{\text{be}}\,{\text{same}}\,{\text{as}}\,\frac{{ {6 \times 3} }}{{10}} \cr }$$
Thus, Required remainder and unit digit will be 8.

This Question Belongs to Arithmetic Ability >> Number System

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Comments ( 1 )

  1. Lorenbenimarena Yanthan
    Lorenbenimarena Yanthan :
    4 years ago

    690031÷777 solve in order

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