=9×2

= 18

There are 18 story books.

54- 18=36

There are 36 comic books.

Extended data multiplication algorithm;

(1) number alignment. Starting from the right, multiply the first factor by the number on each bit of the second factor, and the end of the number will be aligned with which bit of the second factor.

(2) Then add up the numbers multiplied several times.

(Multiply with 0 at the end of an integer: you can multiply the number before 0 first, then see how many zeros are at the end of each factor, and add a few zeros at the end of the multiplied number. )