math

posted by .

The 20 leaves of a 40-page book are numbered 1 through 40. The first and last leaves are ripped out. What is the sum of the remaining page numbers?

  • math -

    So what is the sum of 3+4+5+...37+38 ?

    It is an arithemetic sum, first term 3, d=1
    http://en.wikipedia.org/wiki/Arithmetic_progression

    n= 36 terms

    Sum= n/2 (2a+(n-1)d)

  • math -

    I got 738

  • Math -

    738

    Using the formula of an Arithmetic Progression, we can solve the answer.

    Since 1+2+3+4+...+37+38+39+40 = 41*20 = 820,
    the answer is 820-40-39-2-1 = 738.

    (If there are N pages in a book, there are N/2 leaves)

    Hope I helped!

    Milowen

Respond to this Question

First Name
School Subject
Your Answer

Similar Questions

  1. Math

    A book has n consecutive pages torn out (each paper in a book has two sides - each side is one page). Suppose A is the last numbered page before the torn out section and B is the first numbered page following the torn-out section. …
  2. math

    A student opens a mathematics book to two facing pages. The product of the pages numbers is 420. Find the page numbers. The first page is ?
  3. algebra

    A student opens a math book to two facing pages.The product of the page numbers is 210.Find the page numbers. The first page is _________ The second page is________
  4. Math/Algebra

    A student opens a mathematics book to two facing pages. The product of the page number is 420. Find the page numbers. The first page is ____ The second page is ____
  5. algebra

    A book has N consecutive pages torn out. Suppose A is the last numbered page before the torn out section and B is the forst numbered page following the torn out section. Fins the formula for N in terms of A and B * Each paper in the …
  6. math

    The sum of the page numbers on the facing pages of a book is 457. Find the page numbers?
  7. algebra

    A student opens a mathematics book to two facing pages. The product of the page number is 2352. Find the page numbers. The first page is__________ The secnd page is__________
  8. Math

    Pages in a book are numbered in typical fashion, starting with !. The folio for page 10 will contain the tenth and eleventh digits necessary to paginate the book. On what page will the 2009th digit occur?
  9. Math

    Pages in a book are numbered in typical fashion, starting with !. The folio for page 10 will contain the tenth and eleventh digits necessary to paginate the book. On what page will the 2009th digit occur?
  10. algebra

    The sum of two page numbers on facing page of a book is 81. What are the page numbers

More Similar Questions