number properties Flashcards
real numbers
all numbers in the number line
positive and negative, decimals, integers and fractions
integers
all numbers that are not fractions or decimals
i.e 0, 1, 2, -15
rational numbers
all the numbers that can be expresses as the ratio of two integers
- all integers and fractions
irrational numbers
- square root of 3
3. 14 (pi)
rules for even and odds
odd +- odd= even
even +- even= even
odd+- even= odd
oddodd= odd
eveneven=even
odd*even=even
exponent rules for odds and even
odd^ any positive int= odd
even^ any positive int= even
the reciprocal of a number between 0 and 1 is always
greater than the number
i.e. 2/3 an its reciprocal is 3/2
3/2>2/3
the reciprocal of a number between -1 and 0
is less than the number itself
square number between 0 and 1
is less than the number itself
multiplying any positive number by a fraction between 0 and 1
gives the product smaller than the original number
multiplying any negative number by a fraction between and 1
gives the product greater than the number itself
multiple/factor= integer
i.e 36/6
36/2
36/4
36/9
multiple
factor
multiple is the product of a given integer and another integer i.e 9*2=36
36 is a multiple of 9 and 2
factor or divisor is an integer that divides another integer without leaving remainder
sum of n consecutive terms
mean*number of terms
mean= the average of the first number and the last
=(a1+an/2) *n
if n is odd the sum of the consecutive integer is always divisible by n
9+10+11= 30
n=3
30/3=10
if n is even the sum of the consecutive integers is never divisible by n
9+10+11+12=42
42 is not divisible by 4
product of n consecutive integers is always divisible by n!
345*6=360 which is divisible by 4! = 24
evenly spaced set or arithmetic progression
is a sequence of numbers such that the difference of any two successive members of the sequence is constant
i.e 9, 13, 17, 21
how to calculate the nth term of the sequence
an=a1 +d(n-1)
a1= first term
d= common difference of the successive number
in evenly spaced set/ arithmetic mean the average is calculated
mean/average = median
=a1+an/2
a1=first term
an= last term
if evenly spaced set contains odd number of elements then median is
the middle number and the sum is middle number * number of terms i.e 1, 7, 13, 19, 25 median= 13 sum= 13*5= 65
comparing fractions
when the numerator is the same and de
bigger the denominator smaller the fraction
average arithmetic mean
sum of the terms/ number of the terms
18+21+45/3
range
last number - first number
perfect squares will always have odd number of factors
i.e 4- 1, 2, 4
9- 1, 3, 9