Nice table of Divisibility Rules from 2 to 13 from www.satmath4u.com

www.satmath4u.com

A number is divisible by:	If:
2	The last digit is even (0, 2, 4, 6, or 8).
3	The sum of the digits is divisible by 3.
4	The number formed by the last two digits of the original number is divisible by 4.
5	The number ending in a 0 or a 5.
6	The number is divisible by both 2 and 3.
7	The last digit of the number is multiplied by 2 and subtracted from the rest of the number and the answer is either 0 or divisible by 7.
8	The last three digits form a number divisible by 8.
9	The sum of the digits is divisible by 9.
10	The last digit is 0
11	You add every second digit and then subtract all other digits and the answer is zero or a multiple of 11.
12	The number is divisible by both 3 and 4.
13	You remove the last digit from the number, then subtract 9 times the deleted digit from the remaining number. If what is left is divisible by 13, then so is the original number.

New forums at www.satmath4u.com

There are four new forums

SAT Math Number and Operations  http://www.satmath4u.com/forums/2-SAT-Math-Number-and-Operations

Related to Arithmetic word problems,percent, ratio, and proportion. Properties of integers ,even, odd, prime numbers, divisibility. Rational numbers. Sets:union, intersection, elements. Counting techniques, Sequences and series,exponential growth Elementary number theory

SAT Math Algebra and Functions   http://www.satmath4u.com/forums/4-SAT-Math-Algebra-and-Functions

Related to Substitution and simplifying algebraic expressions, Properties of exponents, Algebraic word problems, Solutions of linear equations and inequalities, Systems of equations and inequalities, Quadratic equations, Rational and radical equations, Equations of lines, Absolute value, Direct and inverse variation, Concepts of algebraic functions, Newly defined symbols based on commonly used operations.

SAT Math Geometry and Measurement  http://www.satmath4u.com/forums/5-SAT-Math-Geometry-and-Measurement

Related to Area and perimeter of a polygon, Area and circumference of a circle, Volume of a box, cube, and cylinder, Pythagorean Theorem and special properties of isosceles, equilateral, and right triangles, Properties of parallel and perpendicular lines, Coordinate geometry, Geometric visualization, Slope, Similarity, Transformations.

SAT Math Data Analysis, Statistics, and Probability  http://www.satmath4u.com/forums/6-SAT-Math-Data-Analysis-Statistics-and-Probability

Related to Data interpretation, tables and graphs Descriptive statistics, mean, median, and mode, Probability.

sat math question division remainder

division remainder

Which of the following is the remainder when [tex]6^2 \cdot 4^2 is divided by 7?
(A) 0
(B) 1
(C) 2
(D) 5
(E) 6

the answer is here
http://www.satmath4u.com/threads/82-division-remainder

SAT probability question

Four fair coins are tossed. Find the probability that all of them will come up tails ?

The answer is here:
http://www.satmath4u.com/threads/76-SAT-probability-question

The probability thatall of them will come up tails means:

TTTT

There is only one way to get four tails - the first toss is tails, the second is tails, the third is tails and the fourth is tails.

Due to the multplication principle (When two or more compound independent events occur, we use multiplication to determine their probability. To find the probability that first event happens and second event happens, we should multiply the probability that the first event happens times the probability that the second event happens. ) we have that the probability of TTTT occurring is 

=

SAT math - Operations with fractions

SAT math - Operations with fractions

Adding and Subtracting Fractions

To add or subtract fractions, here are some steps:

Find the lowest common denominator (LCD) or any common denominator of the fractions.
Convert the fractions to equivalent fractions having the LCD or the common denominator.
Add or subtract the numerators, keeping the denominator the same.
Example:



Solution:

The LCD of 3 and 5 is 15.

Change the fractions so that each has 15 as the denominator. Remember, you have to multiply the numerator and the denominator by the same number, so that you don’t change the value of the fraction.



and finally add the numerators, but keep the denominator the same




Multiplying and Dividing Fractions

The method is to multiply all the numerators of the fractions together to give the numerator of the answer and
similarly multiply all the denominators together to find the denominator of the answer.

Example:




Dividing fractions involves changing the division into a multiplication and then
proceeding as when multiplying fractions. This is achieved by turning the second
fraction upside down and then multiplying instead of dividing.

Example:

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