The answer process is as follows:

(1) There are 45 books in the known book corner, of which two fifths are story books, that is, story books account for two fifths of the total. The number of story books needs multiplication, and the mathematical expression is: 45×2/5.

45×2/5 This is the multiplication of fractions. Integer 45 and denominator 5 are divisible. After division, 45 becomes 9 and the denominator becomes 1. So 45×2/5=9×2= 18 (Ben).

Extended data:

Multiplication rule of fractions:

1. When a fraction is multiplied by an integer, the numerator of the product is multiplied by the numerator of the fraction and the integer, and the denominator remains unchanged. Cut if you can.

2. Fraction multiplied by fraction, numerator multiplied by numerator, denominator multiplied by denominator can be subtracted first.

Law of fractional division:

1. The numerator of the dividend is multiplied by the denominator of the divisor as the numerator;

2. Multiply the numerator of the dividend by the denominator of the dividend. (that is, the dividend is a constant, which is the reciprocal of multiplication and division)