Question

Tính nhẩm.

a) 80 + 20                                b) 500 + 200

    70 + 50                                    800 – 400

    160 – 90                                  320 + 300  

    220 – 50                                  670 – 500 

Answer 1

a) 80 + 20 = 100                                  b) 500 + 200 = 700

    70 + 50 = 120                                      800 – 400 = 400

    160 – 90 = 70                                      320 + 300 = 620

    220 – 50 = 170                                    670 – 500 = 170