# More fun in 2016, Part 10

Algebra Level 4

$1-3+6-10+\cdots-1953+2016= \, ?$

Details and Assumptions

• The expression above shows an alternating sum is running through the triangular numbers.

• A triangular number is denoted by $$T_n = 1 + 2 + 3 + \cdots + n$$. As an explicit example, $$T_{10} = 1+2+\cdots+10=55$$.

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