Divisibility Rules and Subtraction

In this video, Mr. J explains the divisibility rule for seven, which involves doubling the last digit of a number and subtracting it from the remaining number. If the result is divisible by seven, then the original number is also divisible by seven. The video provides four examples to demonstrate this rule: 574, 147, 3976, and 9822. Through these examples, viewers learn how to apply the rule and determine whether a number is divisible by seven without a remainder.

What is the main purpose of checking divisibility?

• To calculate the square root of a number

• To find the largest number

• To determine if a number can be divided without a remainder

• To check if a number is even

What is the first step in the divisibility rule for 7?

• Subtract the last digit from the remaining number

• Double the last digit and subtract it from the remaining number

• Double the last digit and add it to the remaining number

• Add the last digit to the remaining number

In Example 1, what is the result of 57 minus 8?

• 49

• 50

• 47

• 48

Why is 147 divisible by 7?

• Because 14 minus 14 equals 0

• Because 14 minus 7 equals 7

• Because 14 times 7 equals 98

• Because 14 plus 7 equals 21

What is the remaining number after subtracting 12 from 397 in Example 3?

• 385

• 387

• 395

• 375

What is the result of 38 minus 10 in Example 3?

• 18

• 20

• 30

• 28

In Example 4, what is the result of 982 minus 4?

• 974

• 976

• 980

• 978

What is the final result of 97 minus 16 in Example 4?

• 81

• 83

• 79

• 85

Why is 9822 not divisible by 7?

• Because 81 is not divisible by 7

• Because 81 is divisible by 7

• Because 82 is not divisible by 7

• Because 82 is divisible by 7

What is the key takeaway from the divisibility rule for 7?

• It is a complex method for advanced math

• It only works for numbers less than 1000

• It is only applicable to even numbers

• It simplifies checking divisibility for any number