State Whether Each Number Below Is Divisible By 2,3,5,9,10 Or None.
Some Numbers May Have More Than One Divisor.
111
288
52
4805
This is a good exercise in division. Is there a specific problem you are having that we can help you with? Otherwise, just divide by each possible divisor and you have your answer. For example:
111 is divisible only by 3
288 is divisible by 2, 3, and 9.
I'll let you work out the last two.
-Dan
Hello, Ricky!
State whether each number below is divisible by 2,3,5,9, or 10, or None.
(a) 111 . . (b) 288 . . (c) 52 . . (d) 4805
What's stopping you?
Don't you have a calculator . . . or a pencil?
Okay, they must expect you to know some Divisibility Tests
. . so you can simply "eyeball" the numbers.
You already know some of them . . . right?
. . A number is divisible by 2 if it is even (its last digit is even).
. . A number is divisible by 3 if the sum of its digits is divisible by 3.
. . A number is divisible by 5 if it ends in 0 or 5.
. . A number is divisible by 9 if the sum of its digits is divisible by 9.
. . A number is divisible by 10 if it ends in 0.
(a) 111
It ends in "1", an odd number . . . not divisible by 2.
The sum of its digits is: .1 + 1 + 1 = 3, which is divisible by 3.
. . Hence, 111 is divisible by 3.
The last digit is not 0 or 5 . . . not divisible by 5 or 10.
The sum of its digits is 3, which is not divisible by 9.
. . Therefore, 111 is divisible by 3 (only).
(b) 288
It ends in "8", an even number . . . divisible by 2.
The sum of its digits is 2 + 8 + 8 = 18 . . . divisible by 3 and by 9.
. . Hence, 288 is divisible by 3 and 9.
It does not end in 0 or 5 . . . not divisible by 5 or 10.
. . Therefore, 288 is divisible by 2, 3, and 9.
Got it?