n1 is 7654321
n2 is -7891234
n3 is 99999999999999999999999999999
n4 is -1
n5 is 0

abs( n2 ) = 7891234
whereas n2 remains at -7891234
7654321 + -7891234 = -236913

7654321 - -7891234 = 15545555

99999999999999999999999999999 + -1
= 99999999999999999999999999998

7654321 + 9 = 7654330

7654321 - 9 = 7654312

9 - 7654321 = -7654312

7654321 - -9 = 7654330

-7891234 + 10000 = -7881234