Number Properties Flashcards
An integer is divisible by 3 if
the sum of the integer’s digits is divisible by 3
An integer is divisible by 4 if
the integer is divisible by 2 twice or the last two digits are divisible by 4
23,456 is because 56 is divisible by 4
An integer is divisible by 6 if
It is divisible by both 2 and 3 48 by 3 since (4 + 8=12)
An integer is divisible by 8 if
it is divisible by 2 three times or if the last three digits are divisible by 8
23,456 since 456 is divisible by 8
An integer is divisible by 9 if
the sum of the integer’s digits is divisible by 9
4,185
4+1+8+5=18
What re the first ten prime numbers?
2, 3, 5, 7, 11, 13, 17, 19, 23, 29
If a is a factor of b, and b is a factor of c, is a a factor of c?
Yes. Any integer is divisible by all of its factors-and it is also divisible by all of the factors of its factors.
Even + Even =
Even
Odd + Odd =
Even
Even + Odd =
Odd
Even x Even =
Even
Even x Odd =
Even
Odd x Odd =
Odd
Even x Odd x Odd =
Even
If an integer has an odd number of factors
it’s a perfect square
