Divisibility Rules and Concepts

The video tutorial explains the rules of divisibility for various numbers, including 2, 3, 4, 5, 9, 10, and 11. It covers how to determine if a number is divisible by these numbers using specific rules, such as checking the last digit or summing the digits. The tutorial also provides examples to illustrate these rules, helping viewers understand how to simplify fractions by identifying common divisors.

What is a prime number?

• A number divisible by 5 and 10

• A number divisible by any number

• A number divisible by 2 and 3

• A number divisible by 1 and itself only

Which of the following numbers is a prime number?

• 9

• 7

• 6

• 4

A number is divisible by 2 if it ends in which of the following digits?

• 2, 3, 5, 7, 11

• 0, 2, 4, 6, 8

• 1, 2, 3, 4, 5

• 1, 3, 5, 7, 9

Which of these numbers is divisible by 2?

• 47

• 71

• 56

• 33

To check if a number is divisible by 3, what should you do?

• Check if it ends in 0 or 5

• Add its digits and see if the sum is divisible by 3

• Divide it by 2 and check the remainder

• Check if it ends in an even number

Is the number 123 divisible by 3?

• Yes

• No

• Only if it ends in 3

• Only if it ends in 0

What is the sum of the digits of 462, and is it divisible by 3?

• 12, No

• 14, No

• 14, Yes

• 12, Yes

How can you simplify checking divisibility by 3 for large numbers?

• Divide the number by 3 directly

• Check if the number ends in 3

• Add the digits repeatedly until a single-digit number is obtained

• Multiply the digits together

What is the sum of the digits of 25,344, and is it divisible by 3?

• 18, Yes

• 18, No

• 19, Yes

• 19, No

A number is divisible by 4 if the last two digits are divisible by?

• 5

• 4

• 3

• 2