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乘数是一位数的珠算乘法是多位數珠算乘法的基础虼?教好乘数是一位数的珠算乘法是十分重要的。教学乘数是一位数的珠算乘法,多觉得非抓住三个关鍵不可,这就是:①正确熟练的珠算加法;②被乘数与积的定位;③口訣的运用。下面就这三方面分別谈谈我的看法和做法。(一)加法是乘法的基础。譬如“78×7”这道題,如果学生对于加9和加1的知识和技能沒有掌握的话,那么在被乘数个位“8”与乘数“7”相乘得“56”后,第二步被乘数十位“7”与乘数相乘得“49”(490)时,其中“9”(90)的打法就一定成問題了;反之,如果学生熟练地掌握了加法的话,就能自如地运用“九上四去五进一”和“一下五去四”这两句口訣去处理这个“9”(90)了。基于上述原因,我在教乘法之前,十分重視加
The abacus multiplier is one-digit abacus multiplication is the basis of multi-digit abacus multiplication? It is important to teach abacus multiplication that the multiplier is a single digit. Teaching multiplier is a one-digit abacus multiplication, feel more than non-seize the three key points, which is: ① the correct abacus and abacus; ② is the multiplier and product positioning; ③ the use of formulas. The following three aspects of my talk about my views and practices. (A) Addition is the basis of multiplication. For example, the question “78 × 7”, if the students do not have the mastery of the knowledge and skills of adding 9 and 1, then multiplying “8” by the multiplier and multiplying “7” to “56” When the second step is multiplied by a factor of “7” multiplied by “49” (490), the play of “9” (90) must be a problem. Conversely, if the student masters the addition , Then we can freely use the two formulas “nine to four to five into one” and “five to four” to deal with this “9” (90). For the above reasons, before I teach multiplication, I attach great importance to Canada