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初一代数(上)第17页“想一想”,介绍的是两位数乘法的速算,这类两位数的特征是:相乘的两个数,十位上的数字相同,个位上的数字和是10.这类数的特征可简单地概括为“首同尾补”.符合这个条件的两个两位数
The first generation number (above) page 17 “think about it” introduces the fast calculation of two-digit multiplication. The characteristics of these two-digit numbers are: multiplying two numbers, the same number on ten digits, and one digit The sum of the numbers above is 10. The characteristics of such numbers can be simply summed up as “first-end complement”. Two two-digit numbers that meet this condition