Transcript Divisibility Tests

Divisibility Tests
How can you tell quickly whether a
number can be divided exactly by
another?
What does DIVISIBLE
mean?
A number is DIVISIBLE by another number
if there is no remainder after division.
The result after division is a whole number and
the remainder is zero.
eg
36 divided by 12 is 3, so we say
“36 is divisible by 12”
DIVISIBILITY TESTS
Divisibility by 2:
Numbers that end in 0, 2, 4, 6 or 8 can be
divided exactly by 2.
They are said to be divisible by 2, and are also
called EVEN numbers.
Numbers that are not even are called ODD.
DIVISIBILITY TESTS
Divisibility by 3:
To test for divisibility by 3 (without actually
doing the division),
add all the digits together
and if the sum is divisible by 3, then the
original number is too.
This is a “divisibility test for 3”.
DIVISIBILITY TESTS
Divisibility by 4:
A number is divisible by 4 if its last two digits
can be divided by 4.
Can you explain why this is so?
DIVISIBILITY TESTS
Divisibility by 5:
How can you tell by looking at a whole number
if it can be divided by 5?
State a “divisibility test for 5”.
DIVISIBILITY TESTS
Divisibility by 6:
A number that can be divided by 6 needs to be
able to be divided by both 2 and 3.
Now state a “divisibility test for 6”.
DIVISIBILITY TESTS
Divisibility by 11 and others:
Find out about other “divisibility” tests
– eg by 11.
DIVISIBILITY TESTS
Let’s test a number eg 120
2? Yes, because it ends in 0, so is even
3? Yes, because 1 + 2 + 3 = 6, which of course
is divisible by 3!
4? Yes, because 20 can be divided by 4
5? Yes, because it ends in 5 or 0.
6? Yes, because it can be divided by 2 and
by 3.
Test all the numbers on this page for
divisibility by 2, 3, 4, 5, and 6.
Remember some may be divisible by more than
one of these numbers and some may not be
divisible by any of them!
240
27
711
415
256
400
91
50
81
111
23
343
Write down your answers!
108
180