Question

divisiblility test for 11 and 7??​

Answer 1

Answer:

Hey this is you ans....

Your rule fro divisibility by 7 is correct. Thus, for example if the number is 4102 then

410 - 2 2 = 406

so 4102 is divisible by 7 if 406 is divisible by 7. To decide if 406 is divisible by 7 you can apply your rule again.

40 - 2 6 = 28

so 406 is divisible by 7 if 28 is divisible by 7. But 4 7 = 28 so 28 is divisible by 7, and hence 406 is divisible by 7, which insures 4102 is divisible by 7.

For a test of divisibility by 11 start from the right and add every second digit. Now subtract from that total the sum of the remaining digits. The resulting number is divisibly by 11 if and only if the number you started with is divisible by 11.

For example consider 678234.

(4 + 2 + 7) - (3 + 8 + 6) = 13 - 17 = -4

which is not divisible by 11 so 678234 is not divisible by 11. Now try 908193

(3 + 1 + 0) - (9 + 8 + 9) = -22

which is divisible by 11 so 908193 is divisible by 11

Answer 2

Answer:

Divisility rule of 11

Add and subtract digits in an alternating pattern (add digit, subtract next digit, add next digit, etc). Then check if that answer is divisible by 11.

Divisility rule of 7

Double the last digit and subtract it from a number made by the other digits. The result must be divisible by 7. (We can apply this rule to that answer again)