Tính nhanh: a. ( 1+3+5+7+…+2003+2005) x (125 125 x 127 – 127 127 x 125) b. 19,8:0,2x44,44x2x13,2:0,253,3x88,88:0,5x6,6:0,125x5

Tính nhanh:

a. ( 1+3+5+7+…+2003+2005) x (125 125 x 127 – 127 127 x 125)

b. 19,8:0,2x44,44x2x13,2:0,253,3x88,88:0,5x6,6:0,125x5