Question

Calculati:
1+2+3+........... +100
11+22+33+..........+1100
5+10+15+............+150
3+5+7+.............+2017 - 2-4-6-........-2076

Answer 1

1+2+3 + ... + 100 = 100X101/2  = 50x101 = 5050

11+22+33 + .... + 1100 = 11 ( 1+2+3 + ... + 100 ) = 11 x 5050 = 55550

5+10+15+ ...+ 150 = 5 ( 1+2 + 3 + ... + 30) = 5x30x31/2 = 2325

3+5+7 + ... + 2017 = 1009^ 2 - 1 = 1018080

2+4+6+...+2076 = 1038x1039 = 1078482

1018080 - 1078482 = 60402