Question

A=101-100+99-98+...+3-2+1

Answer 1

A= 101-100+99-98+.......3-2+1

A= (101-100) + (99-98) + ... + (5-4) + (3-2) +1 
A= 1 + 1 + ... + 1 + 1 + 1 
A= 1 x 51 
A= 51

Answer 2

A = 101 - 100 + 99 - 98 + ....... 3 - 2 + 1

A = ( 101 - 100 ) + ( 99 - 98 ) + ... + ( 5 - 4 )  + ( 3 - 2 ) +1 
A = 1 + 1 + ... + 1 + 1 + 1 
A = 1 x  51 
A = 51