# 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!

• 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
• 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.

• 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.