Numbering of pages in the book required 2323 figures. The first two pages, the last and also the beginning of each chapter are not numbered from them. In total in the book five chapters. The first begins on the 3rd page, and the second ā on the 99th. How many pages in the book?

90
It is the algebraic sequence. formula alg. progressions such is a with n+1 = a nĀ  + d d = 1 since increases by 1, but it works only up to 10, at the press 10 and big figure 2 figures and 2 = and are necessary for 1 + 1 to and to 9 = and to 1 + 1*9 to and 9 = 10 further we use the same progression, d will be equal 1, but 2 figures will be printed already, we print 2 figures in an interval [10;99] then of and 10 = and 1 + (1*9) + (1*1)2 and 10 = 1 + 9 + 2 and 10 =12 and 99 = and 1 + (1*9) + (1*90)2 and 99 = 190 for numbers [100;999] will spend now 3 figures, means and 100 = and 1 + (1*9) + (1*90)2 + (1*1)3 and 100 = 1 + 9 + 180 + 3 and 100 = 193 and 999 = and 1 + (1*9) + (1*90)2 + (1*900)3 and 99 9 = 1 + 9 + 180 + 2700 and 999 = 27190 to us needs to find and x which will be equal 2323, then 2323 = 1 + 9 + 180 + 2133 2133 = 1 + 9 + 180 + (1*kh) 3 2133 = 190 + the 3rd of the 3rd = 2133 - 190 of the 3rd = 1943 x ā 648 Means in the book of 648 pages
343