1× 9 = 9 (pieces);
10 ~ 99 pages have two digits, * * * 99-9 = 90 pages, and * * * requires digits.
2× 90 = 180 (piece);
The page number of 100 ~ 400 pages is three digits, * * * 400-99 = 30 1 page, and * * * requires digits.
(400-100+1) × 3 = 301× 3 = 903 (pieces).
In a word, this book needs to be digitized.
9+ 180+903 = 1092 (pieces).
The number of times that Math 3 appears in the page number can be considered in three situations:
When the unit mathematics is 3, there are 0 ~ 9, 10 digits in decimal places, and 0 ~ 3, 4 digits in hundredth digits, so * * *
4× 10 = 40 (times);
When the decimal mathematics is 3, there are 0 ~ 9, 10 digits to fill the unit, and 0 ~ 3, 4 digits to fill the hundred digits, so * * *
4× 10 = 40 (times);
When the numerator is 3, there are 0 ~ 9, 10 species to fill in decimal places, and 0 ~ 9, 10 species to fill in single digits, so * * *
10× 10 = 100 (times).
Therefore, the number of times that Math 3 appears in the page number is:
40+40+ 100 = 180 times.