《数学课程标准》指出:“数学教学应重视口算,加强估算,鼓励算法多样化……”由此曾经“可有可无”的估算教学摆到了人们面前。然而由于功利性因素的干扰、应试教育的导向,以及一些教师“精确计算”的惯性思维作祟,使得“估算”尽管有《数学课程标准》的保驾护航,尽管有名家大 The Mathematics Curriculum Standard states: “Mathematics teaching should lay stress on oral arithmetic, strengthen the estimation, encourage the diversity of algorithms,” and “once” “optional” estimation teaching has been put on the scene. However, due to the interference of utilitarian factors, the orientation of exam-oriented education and the inertial thinking of some teachers “exact calculation ” makes “estimation ” despite the math curriculum standard escort, despite the famous