/sci/ - Science & Math

>>11976667
sum 1 to a where a is even : (a-0)+1 + (a-1)+2 + ... + ((a/2)+(a/2+1)) = (a/2)*(a/2+1)
sum 1 to 100 : 100+1 + 101+2... + 50+51 = 101*50 = 5050