Question

tính nhanh: 2+4+6+8+...+100

Answer 1

2+4+6+8+...+100

=(100+2) *2 :2  = 102

Answer 2

 100+2=98+4=96+6=.....gom 25 cặp

Nên ta lấy 

(2 + 100 ) * 25 = 2550 

Answer 3

2+4+6+8+...+100=(100+2) *2 :2  = 102