Divisibility rule of 11.
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Answer:
Divisibility Rule for 11
Let’s say that we want to determine if 31823 is evenly divisible by 11. I will know that it is evenly divisible by 11 if 3 – 2 + 8 – 1 + 3 is evenly divisible by 11. 31823 is divisible by 11 because 3 – 2 + 8 – 1 + 3 is equal to 11.
Let’s try 9123: 3 – 2 + 1 – 9 = -7. Since -7 is not divisible by 11, 9123 is not evenly divisible by 11.
Let’s try one more together to make sure you understand the pattern. Is 9876543210 divisible by 11? Since 0 – 1 + 2 – 3 + 4 – 5 + 6 – 7 + 8 – 9 = -5 and -5 is not evenly divisible by 11, 9876543210 is not evenly divisible by 11.
Okay, so now that we understand the pattern, how do we find a nearby number that is divisible by 11? Believe it or not, you just have to subtract the number that you get from our math problem to the original number, to get one that is divisible by 11.
Let’s use 9123. 3 – 2 + 1 – 9 gave us -7. Using that number, we can do the following: 9123 – (-7) = 9123 + 7 = 9130. This means that 9130 is evenly divisible by 11.
Now let’s try our other number that wasn’t divisible by 11: 9876543210. We will subtract -5 which came from 0 – 1 + 2 – 3 + 4 – 5 + 6 – 7 + 8 – 9. Using that number, we will find the answer by doing this: 9876543210 – (-5) = 9876543210 + 5 = 9876543215. That means that 9876543215 is evenly divisible by 11.
Answer:
☞ If the number of digits is even, add the first and subtract the last digit from the rest. The result must be divisible by 11. If the number of digits is odd, subtract the first and last digit from the rest. The result must be divisible by 11.
Drop some thnx ❤️