Caveman Chang SHORCUTS with Divisibility Rules PART 2

Please check out my first video for the Divisibility Rules for numbers 1 to 4. https://rumble.com/vjq9p9-caveman-chang-demonstrates-divisibility-rules-aka.-another-math-shortcut.htmlShow more

For this video, we went over the Divisibility Rules for numbers 5 to 12. Please know that there are many more divisibility rules (e.g. 13, 14, etc.) Check out the video for examples and practice problems!

Rule for #5: Check the last digit of the original number to see if it ends in a 5 or 0. If it ends in a 5 or 0, the original number can be divisible by 5.

Rule for #6: Check to see if the original number is divisible by 3 and 2. If the original number is divisible by 3 and 2, the original number can be divisible by 6.

Rule for #7: Get the last digit of the original number and multiply it by 2. Take the remaining numbers and subtract the last digit that was multiplied by 2. If the result is divisible by 7, the original number can be divisible by 7.

Rule for #8: If the original number is larger than 3 digits, take the last 3 digits and see if that number is divisible by 8. If the last 3 digits are divisible by 8, the original number can be divisible by 8. If the original number is 3 digits or less, you have to check by dividing the original number by 8.

Rule for #9: Take the individual digits of the original number and add them together. If the sum of the digits is divisible by 9, the original number can be divisible by 9.

Rule for #10: Check the last digit of the original number to see if it ends in a 0. If it ends in a 0, the original number is divisible by 10.

Rule for #11: Get the alternating digits (1st, 3rd, 5th, etc.) and add them together. Add the rest of the alternating digits (2nd, 4th, 6th, etc.) together. Take the difference between the sum of the two sets of alternating digits and see if that number is divisible by 11. If the difference is divisible by 11, the original number is divisble by 11. It does matter in which order you subtract the sums of the alternating digits.

Rule for #12: Check to see if the original number is divisible by 3 and 4. If the original number is divisible by 3 and 4, the original number can be divisible by 12.

Practice Problems:
Level 1: 636,482,790 is divisible by both 5 and 10.
Level 2: 33,822 is divisible by 3, 6, and 9.
Level 3: 9,506,112 is divisible by 77.

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