Question

Find the value of 5 + (-5) + 5+ (-5) + 5 + ....... if the number of fives are
(i) 148
(ii) 191​

Answer 1

  5 + (– 5) + 5 + (– 5) + 5 ......

=  (5 – 5) + (5 – 5) + 5........

=   0 + 0 + 0 + 0 + 5......

=   5

Number of 5 in [5 + (– 5) + 5 + (– 5) + 5] is five.

AND five is odd number.

and it's soluction is 5.

  5 + (– 5) + 5 + (– 5) + 5 + (- 5) ......

=  (5 – 5) + (5 – 5) + (5 – 5).......

=  0    

Number of 5 in [5 + (– 5) + 5 + (– 5) + 5 + (- 5)] is Six.

AND six is even number.

and it's soluction is 0.

We observed that, when number of five is odd answer = 5

and when it is even answer = 0

question 1.) 148

148 is even number then, answer = 0

question 2.) 191

191 is odd number then, answer = 5