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 .
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How can you tell quickly whether a number can be divided exactly by another?
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 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 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 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 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 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 by 11 and others:
Find out about other “divisibility” tests
– egby 11.
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
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 27 256 81
Write down your answers!