Divisibility Flashcards
1
Q
Divisibility of 3
A
Sum of digits divisible by 3
2
Q
Divisibility of 4
A
Last two digits divisible by 4; or divisible by 2, twice
3
Q
Divisibility of 6
A
Divisible by 2 and 3
4
Q
Divisibility of 7
A
(All digits ex last) - (last digit x 2) is divisible by seven
5
Q
Divisibility of 9
A
Sum of digits is divisible by 9
6
Q
Divisibility by 11
A
Sum of odd digits - sum of even digits
7
Q
What are the prime numbers?
A
2, 3, 5, 7, 11, 13, 17, 19
8
Q
How do you get to the LCM
A
Multiply all the prime factors of the two numbers together (matching primes vertically when possible). If two numbers don’t contain any prime factors (i.e. they are primes), then
9
Q
Divisibility of 8
A
Last three digits divisible by 8, or divisible by 2 three times
