Question

Find the unit digit of the following exponential numbers:

(i) 106²¹

(ii) 25⁸

(iii) 31¹⁸

(iv) 20¹⁰

Answer 1

(i) 106²¹ Unit digit of base 106 is 6 and the power is 21 and is positive.

Thus the unit digit of 106²¹ is 6.

(ii) 25⁸ Unit digit of base 25 is 5 and the power is 8 and is positive.

Thus the unit digit of 25⁸ is 5.

(iii) 31¹⁸ Unit digit of base 31 is 1 and the power 18 and is positive.

Thus the unit digit of 31¹⁸ is 1.

(iv) 20¹⁰ Unit digit of base 20 is 0 and the power 10 and is positive.

Thus the unit digit of 20¹⁰ is 0.