口算是珠算、笔算的基础，学生具备一定的口算能力，便于理解笔算的算理，提高计算速度。同时，口算也是计算能力的一个重要方面，必须予以重视。一、培养类推能力。在教学两位数加减法时，先复习两位数加减整十数，再进行加减一位数的口算，然后启发学生把两位数加减两位数改 Mouth count is abacus, pen basis, students have a certain ability to calculate, easy to understand the arithmetic of pen calculation, improve the calculation speed. At the same time, accounting is an important aspect of computing power and must be given due attention. First, develop analogy. In the teaching of double-digit addition and subtraction, the first review of double-digit addition and subtraction of the whole number, then add and subtract one-digit port count, and then inspired students to double-digit double-digit change