Calculation 1-2 + 3-4 + 5-6 +... - 2004 + 3005=

Calculation 1-2 + 3-4 + 5-6 +... - 2004 + 3005=

Well, are you sure the last one is 3005 instead of 2005? I'll show you both cases. 1. If the last one is 2005, you can divide the two into two groups, which can be divided into 2004 / 2 = 1002 groups, namely: (1-2) + (3-4) + (5-6) +... + (2003-2004) + 2005 = (- 1) * 1002 + 2005 = 2005-1002 = 100

How much is (1 + 2) * ((1 + 2) * 3)% 10?

=3*3*3%*10
=27%*10
=2.7

2004 * (1:1-2) * (1:1-3) * (1:1-3) * (1:1-4) *. * (1:1-2004)

[one third more]
2004 * (1:1-2) * (1:1-3) * (1:1-4) *. * (1:1-2004)
=2004 * 2:1 * 3:2 * 4:3 *... * 2004 * 2003
[you can make an appointment in the middle]
=2004 * 1 / 2004
=1