# witch of these numbers is/are divisable by both 3 and 5 they are 3040,4050,2315,4245?

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4050, 4245.

=)

4050 (3 x 1350) (5 x 810)

4245 (3 X 1415) (5 x 849)

To figure out if a number is divisible by 5, check out the last digit (the digit in the 'ones' place). Numbers that end in '5' or '0' are divisible by 5

To figure out if a number is divisible by 3, add the digits; keep adding until you get a 1 digit number. If the sum of the digits is 3, 6, or 9, the number is divisible by 3.

All 4 numbers end in '0' or '5', so they are all divisible by 5.

Which are divisible by 3? Add the digits to find out.

3 + 0 + 4 + 0 = 7; 7 isn't 3 or 6 or 9

4 + 0 + 5 + 0 = 9; 9

2 + 3 + 1 + 5 = 11; 1 + 1 = 2

4 + 2 + 4 + 5 = 15; 1 + 5 = 6

enjoy!

• eric l
Lv 6

If it ends in a 0 or a 5, it is divisible by 5. Add up all the digits, if they add up to a number divisible by 3, then the number is divisible by 3.

All the numbers listed above are divisible by 5.

Here is the analysis for 3;

3+0+4+0=7

7 is not divisible by 3 therefore 3040 is not divisible by 3

4+0+5+0 = 9

9 is divisible by 3 therefore 4050 is divisible by 3.

2+3+1+5=11

11 is not divisible by 3 therefore 2315 is not divisible by 3.

4+2+4+5=15

15 is divisible by 3 therefore 4245 is divisible by 3.

They are all divisible by 5 as they all end in a multiple of 5. 4050 and 4245 are the only ones which are also divisible by 3.

Source(s): calculator
• Tish
Lv 5

I refuse to do your homework for you, because you'll never learn that way, but I'll tell you this much...

If you add the digits in a number, and the result is divisible by 3, the whole number is divisible by 3. For example: 8571 8+5+7+1 = 21. 21 is divisible by 3, therefore 8571 is also divisible by 3.

As for what's divisible by 5, the answer is all in the last digit.

You're on your own...have fun. :) And remember - knowledge is power.

• Kyrix
Lv 6

A number divisible by 5 would end in a 0 or 5... all four numbers meet this requirement.

A number divisible by 3 would have the sum of its digits be divisible by 3 as well.

3040 -> 7

4050 -> 9

2315 ->11

4245 -> 15

4050 and 4245 are both divisible by three, so those are your two answers.

They are all divisible by five.

4050 and 4245 are divisible by 3.

So 4050 and 4245 are the only ones divisible by both 3 and 5.