RRB Assistant Loco Pilot and Technician Model Paper 1 with solutions

Question : 6 of 100

Marks: +1, -0

The remainder when

3^{21

is divided by 5 is

Solution:

(c)

3^1= 3

;

3^2= 9

;

3^3= 27

;

3^4= 81

;

3^5= 243

i.e. unit’s digit is repeated after index 4.
Remainder after dividing 21 by 4 = 1
∴ Unit’s digit in the expansion of

(3)^{21}

= 3
∴ Remainder after dividing by 5 = 3

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