Math facts for GRE

  1. even + even = even * even =
    odd + odd = odd * odd =
    even + odd = even * odd =
    • even + even = even even * even = even
    • odd + odd = even odd * odd = odd
    • even + odd = odd even * odd = even
  2. prime numbers through 30
    2, 3, 5, 7, 11, 13, 17, 19, 23, 29
  3. divisibility
    • by 3 if sum of digits = 3
    • by 4 if last two digits of the number are divisible by 4
    • by 5 if it ends in 0 or 5
    • by 6 if its divisible by both 2 and 3
    • by 8 if the last 3 digits form a number divisible by 8
    • by 9 if the sum of the gidits is divisible by 9
  4. Rules of Exponents
    a2 = a * a

    a2 * a3 = a2+3 = a5

    (a2)3 = a6

    a2/a3 = a2-3 = a-1 = 1/a

    1512 - 1511 = 1511(15-1) = 1511(14)
  5. Rules of Square Roots
    • can mult and divide square roots by each other
    • can only add/subtract intigers in fromt of root if its the SAME root
    • on GRE square root only includes the positive answer, but can square neg numbers to equal positive number
  6. square root of 2 =

    square root of 3 =
    square root of 2 = 1.4

    square root of 3 = 1.7
  7. Quadratic Equations
    x2- y2 = (x + y)(x - y)

    (x + y)2 = x2 + 2xy + y2

    (x - y)2 = x2 - 2xy + y2
Author
csawic
ID
108750
Card Set
Math facts for GRE
Description
math facts for gre
Updated