Examples with solutions for Divisibility Rules for 2, 4 and 10: Arranging the digits

Exercise #1

Rearrange the following digits to create a number divisible by 2:

2, 1, and 3.

Video Solution

Step-by-Step Solution

To solve this problem, let's explore how to form a number divisible by 2 using the digits 2, 1, and 3. A number is divisible by 2 if the last digit is an even number, which, from our given digits, is only the digit 2.

Let's examine all possible permutations of these digits and identify which numbers are divisible by 2:

  • Permutation 1: 213, where the last digit is 3 (not divisible by 2).
  • Permutation 2: 231, where the last digit is 1 (not divisible by 2).
  • Permutation 3: 123, where the last digit is 3 (not divisible by 2).
  • Permutation 4: 132, where the last digit is 2 (divisible by 2).
  • Permutation 5: 312, where the last digit is 2 (divisible by 2).
  • Permutation 6: 321, where the last digit is 1 (not divisible by 2).

From our examination, the numbers 132 and 312 both end in 2, making them divisible by 2. Therefore, the correct choice according to the problem's options is to select both permutations that satisfy the condition.

Therefore, the solution to the problem is Answer b and c.

Answer

Answer b and c.

Exercise #2

Look at the following digits:

5, 3, 7, 4

Create a number using these digits that results in a whole number when divided by 2.

Video Solution

Step-by-Step Solution

To solve this problem, we need to apply the rule of divisibility by 2:

  • A number is divisible by 2 if its last digit is even.

We are given the digits: 5, 3, 7, 4.

Among these digits, the only even digit is 4.

Therefore, to form a number that is divisible by 2, 4 must be the last digit.

From the provided multiple-choice options, we will select the number that ends with 4:

  • Reading each choice, we find that choice 4, "7534," has 4 as the last digit and thus is divisible by 2.

Therefore, the correct number is 7534.

Answer

7534

Exercise #3

Look at the following digits:

8, 1, 3, 7

Create a number using these digits that results in a whole number when divided by 2.

Video Solution

Step-by-Step Solution

To solve this problem, we'll follow these steps:

  • Step 1: Identify and understand the requirement for divisibility by 2.
  • Step 2: Determine the potential numbers by rearranging the digits to satisfy the divisibility rule.
  • Step 3: Confirm by checking the last digit of the arranged number.

Now, let's work through each step:
Step 1: A number is divisible by 2 if its last digit is even. Among the given digits (8, 1, 3, 7), only 8 is even.
Step 2: Rearrange the digits so that the last digit is 8. Potentially, using all digits, the number 1378 can be formed.
Step 3: Check that 1378 ends with 8, confirming it is divisible by 2.

Therefore, the solution to the problem is 1378.

Answer

1378

Exercise #4

Rearranged the following numbers to make a number divisible by 10:

5, 1 ,0, and 2.

Video Solution

Step-by-Step Solution

To solve this problem, we should organize the given digits to make a number that is divisible by 10. According to the rule of divisibility by 10, a number must end in 0.

Let's follow these steps:

  • Step 1: Ensure the number ends in 0 by placing 0 at the unit's place.
  • Step 2: Arrange the remaining digits (5, 1, and 2) to form the largest possible number.
  • Step 3: Arrange 5, 1, and 2 in descending order, resulting in 521.
  • Step 4: Combine the arranged digits with 0 at the end: This gives 5210.

The number 5210 ends with 0, making it divisible by 10.

Therefore, the solution to the problem is 5120 5120 .

Answer

5120

Exercise #5

Rearrange the following digits to create a number divisible by 10:

2, 3 , and 5.

Video Solution

Step-by-Step Solution

To solve this problem, we need to understand the divisibility rule for 1010. A number is divisible by 1010 if and only if it ends in 00.

Given the digits 22, 33, and 55, we need to form a number ending with 00. However, none of these digits is 00. Therefore, using only the digits 22, 33, and 55, it is impossible to create a number that ends in 00.

This means it's impossible to rearrange these digits to form a number divisible by 1010.

Therefore, the correct answer is It is impossible.

Answer

It is impossible.

Exercise #6

Rearrange the following digits to that they form a number divisible by 4:

4, 2, 3 , and 1.

Video Solution

Step-by-Step Solution

To solve this problem, we will apply the divisibility rule for 4:

A number is divisible by 4 if the number formed by its last two digits is divisible by 4. Therefore, we need to consider pairs from the digits 1,2,3,1, 2, 3, and 44 that can form numbers divisible by 4. Let's list them:

  • 12: Not divisible by 4.
  • 21: Not divisible by 4.
  • 32: Divisible by 4 (32÷4=832 \div 4 = 8).
  • 42: Divisible by 4 (42÷4=10.542 \div 4 = 10.5 - Incorrect!).

From the list above, the only pair that forms a number divisible by 4 is 3232. By setting the last two digits as 3232, we use the remaining digits 11 and 44 as the preceding two digits to form the complete number.

Possible numbers using this order include x132x132, where xx is any combination of the remaining 1,41, 4.

Let's attempt to form a number:
Arrange 3,1,2,43, 1, 2, 4: 3131 and 2424, yielding 3124.
Verify if it matches our condition as laid in the answer choices.

Looking through our options, only 31243124 fits a number divisible by 4.

Thus, the number 3124 fulfills the condition of divisibility by 4.

Therefore, the solution to the problem is 3124 3124 .

Answer

3124