1. Imagine a number that is greater than 1 , and keep it in your mind.

2.Multiply that number by 9 and keep the result in your mind.

3.Now, sum the digits of your result.

OK. Let me read your mind..........Yes, the answer in your mind is "9". Sounds crazy?

2.Multiply that number by 9 and keep the result in your mind.

3.Now, sum the digits of your result.

OK. Let me read your mind..........Yes, the answer in your mind is "9". Sounds crazy?

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Comments

this is simplefor any number to be divided by 9 ,the sum of its digits must be 9 or something divided by 9 tootry to multiply any number by 9 and then add the digits of the result all togethersame rule applied for 3. any number to be divided by 3 the sum of its digits must be 3,6,9, or anything dividable by 3good one here[Y]

tattyjackyrishonlyVille_maddengurlCheers!

- Joy

[f]

TearsofjoyrishonlyHere are the divisibility keys that I know -

2 - last digit is an even number

3 - sum of the digits is a multiple of 3. If that number is too long, then sum the digits again and again till you get to a 2-digit or 1-digit number.

4 - last two digits are divisible by 4.

5 - last digit is 5 or 0.

6 - it has to be divisible by 2 and 3(obviously)

7 - none that I know of

8 - last 3 digits are divisible by 8.

9 - sum of the digits add up to 9.

There is one for 11, but it's complicated. I've forgotten it. . Anyway, division by 11 is easy

Cheers,

- Joy

TearsofjoyDivisibility test for 11 - The difference between the sum of the odd numbered digits (1st, 3rd, 5th...) and the sum of the even numbered digits (2nd, 4th...) is divisible by 11.

There's a test for 7 in there too, but I found it really complex. I'd rather divide by 7, thanks!

Cheers,

- Joythegeek.

Tearsofjoy2. double the number?

3. add 100?

4. half the number?

5. take away the number you started with?

6. is your answer 50?

anonymous