Examples
Sum each set of digits:
1_8_3_4 -> 1+8+3+4 = 16
_2_9_2 -> 2+9+2 = 13
Difference between the sums: 16 - 13 = 3, not divisible by 11; so original number 1289324 is not divisible by 11.
Sum each set of digits:
1_4_7_7 -> 1+4+7+7 = 19
_9_0_2_8 -> 9+0+2+8 = 19
Difference between the sums: 19 - 19 = 0; so original number 19407278 is divisible by 11.
To test divisibility for 20, you need to use the tests for divisibility by 4 and 5.The test for divisibility by 4 is that the last 2 digits of the number, given as a 2-digit number, are divisible by 4.Example for 4:We are testing the number 11042.42/4 = 10.5 which is not a whole number. Therefore 11042 is not divisible by 4.The test for divisibility by 5 is that the last digit of the number is either 5 or 0.
The divisibility rule for 22 is that the number is divisible by 2 and by 11. Divisibility by 2 requires that the number ends in 0, 2, 4, 6 or 8. Divisibility by 11 requires that the difference between the sum of the the digits in odd positions and the sum of all the digits in even positions is 0 or divisible by 11.
if the difference of the sum at the alternate places is divisible by 11 then it is divisible by 11
The number must be divisible by 13 and by 11.
no it does not and the smallest missing factor that would allow for divisibility is 13
you can't
To test divisibility for 20, you need to use the tests for divisibility by 4 and 5.The test for divisibility by 4 is that the last 2 digits of the number, given as a 2-digit number, are divisible by 4.Example for 4:We are testing the number 11042.42/4 = 10.5 which is not a whole number. Therefore 11042 is not divisible by 4.The test for divisibility by 5 is that the last digit of the number is either 5 or 0.
Edward Chavez
The divisibility rule for 22 is that the number is divisible by 2 and by 11. Divisibility by 2 requires that the number ends in 0, 2, 4, 6 or 8. Divisibility by 11 requires that the difference between the sum of the the digits in odd positions and the sum of all the digits in even positions is 0 or divisible by 11.
Every number has a test for divisibility. The issue is that the tests get more complicated as the divisor increases. For primes up to 50, see either of the attached links.
all even numbers
If the number is also divisible by 2 and 3
Yes
if the difference of the sum at the alternate places is divisible by 11 then it is divisible by 11
928389 = 11 x 84399
The difference between the last digit and the rest of the number is a multiple of 11
The number must be divisible by 13 and by 11.