What is the sum of 1 times 2 plus 3 times 4 plus 5 times 6 plus 7 times 8 plus 9 times 10 plus. 99 times 100? It's a simple operation

What is the sum of 1 times 2 plus 3 times 4 plus 5 times 6 plus 7 times 8 plus 9 times 10 plus. 99 times 100? It's a simple operation

Let the original formula = m be (1) 1 ^ 2 + 1 + 3 ^ 2 + 3 + 5 ^ 2 + 5 +. + 99 ^ 2 + 99 (2) 2 ^ 2-2 + 4 ^ 2-4 + 6 ^ 2-6 +. + 100 ^ 2-100 (1) + (2) = 2m. Use the formula 1 ^ 2 + 2 ^ 2 + 3 ^ 2 + +n^2=n(n+1)(2n+1)/62M=[100(100+1)(200+1)/6]-50 = 33830M=169150