Question

calculati (2+4+6+...+1994)-(1+3+5+..
1995)

Answer 1

(2 + 4 + 6+.......+ 1994) - (1 + 3 + 5 + .....+ 1995) =
2(1 + 2 + 3 +.....+ 997) - {(1995 + 1) * [(1995 - 1) : 2 + 1] : 2} =
2 * 997 * 998 : 2 - {1996 * [1994 : 2 + 1] : 2} =
1994 * 499 - {1996 * 998 : 2} =
1994 * 499 - {1996 * 499} =
499 * (1994 - 1996) =
499 * (- 2) =
- 998