Question

我会估算。   
328+271≈                            652 - 348≈                      209+687≈     
893 - 401≈                           771 - 168≈                      159+236≈     
461 - 156≈                           579 - 267≈                      486 - 316≈

Answer 1

600；300；900；490；600；400；300；310；170