Digit Sums and Divisibility Rules

Matt with Mr. J explains the divisibility rule for 3, which involves adding all the digits of a number and checking if the sum is divisible by 3. He provides examples with numbers 87, 491, and 56025 to demonstrate the rule. The video concludes with a quick review and a link to a more detailed explanation.

What is the first step in determining if a number is divisible by three?

• Multiply all the digits together.

• Subtract the smallest digit from the largest.

• Divide the number by two.

• Add all the digits together.

If the sum of the digits of a number is 15, is the number divisible by three?

• Yes, because 15 is divisible by three.

• No, because 15 is not divisible by three.

• No, because 15 is a prime number.

• Yes, because 15 is an even number.

For the number 491, what is the sum of its digits?

• 12

• 13

• 14

• 15

Is the number 491 divisible by three?

• Yes, because the sum of its digits is divisible by three.

• No, because it is a prime number.

• No, because the sum of its digits is not divisible by three.

• Yes, because it is an even number.

What is the sum of the digits of 56,025?

• 18

• 19

• 17

• 16