Divisibility Breakdown: Is 10 Always Divisible by 4?

Divisibility Rules with Counterexample Analysis

If a number is divisible by 10, will it therefore be divisible by 4?

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Step-by-step video solution

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00:00 Is a number that is divisible by 10 also divisible by 4?
00:03 Let's take an example of a number divisible by 10
00:09 We can see that this number is not divisible by 4
00:13 Therefore, not every number divisible by 10 is divisible by 4
00:16 And this is the solution to the question

Step-by-step written solution

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1

Understand the problem

If a number is divisible by 10, will it therefore be divisible by 4?

2

Step-by-step solution

We begin by reviewing the divisibility rules:

  • A number is divisible by 10 if and only if its last digit is 0. This implies that the number can be expressed as 10k 10k , where k k is an integer.
  • A number is divisible by 4 if the number formed by its last two digits is divisible by 4. For example, 112 is divisible by 4 because 12 (its last two digits) is divisible by 4.

Let's analyze these conditions:

Since any number that is divisible by 10 ends with a 0, examples would include 10, 20, 30, etc. Look at the last two digits of these numbers:

  • For 10, the last two digits are 10, which is not divisible by 4 (since 104=2.5 \frac{10}{4} = 2.5 ).
  • For 20, the last two digits are 20, which is divisible by 4 (since 204=5 \frac{20}{4} = 5 ).
  • For 30, the last two digits are 30, which is not divisible by 4 (since 304=7.5 \frac{30}{4} = 7.5 ).

From this analysis, it's clear that numbers like 10 and 30 are divisible by 10 but not by 4. Thus, it's possible for a number to be divisible by 10 without being divisible by 4.

Therefore, the answer to the question "If a number is divisible by 10, will it therefore be divisible by 4?" is no.

3

Final Answer

No.

Key Points to Remember

Essential concepts to master this topic
  • Rule: Divisible by 10 means last digit is 0
  • Technique: Check last two digits for divisibility by 4: 10÷4=2.5
  • Check: Test specific examples: 10, 30 divisible by 10 but not 4 ✓

Common Mistakes

Avoid these frequent errors
  • Assuming divisibility by 10 guarantees divisibility by 4
    Don't assume that 10k is always divisible by 4 = wrong conclusion! This ignores that 10 = 2×5, not 4×something. Always test specific examples like 10 and 30 to find counterexamples.

Practice Quiz

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Is the number 43 divisible by 4?

FAQ

Everything you need to know about this question

Why isn't 10 divisible by 4 if it ends in 0?

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Just because a number ends in 0 doesn't mean it's divisible by 4! You need to check the last two digits. For 10, the last two digits are '10', and 104=2.5 \frac{10}{4} = 2.5 , which isn't a whole number.

Are there any numbers divisible by 10 that ARE divisible by 4?

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Yes! Numbers like 20, 40, 80 work because their last two digits (20, 40, 80) are all divisible by 4. The key is checking each case individually.

How do I remember the divisibility rule for 4?

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Easy trick: A number is divisible by 4 if its last two digits form a number divisible by 4. Just focus on those final two digits and divide by 4!

What's the pattern for which multiples of 10 are divisible by 4?

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Look at the tens digit! If it's even (like 20, 40, 60, 80), then it's divisible by 4. If it's odd (like 10, 30, 50, 70), then it's not divisible by 4.

Can I use prime factorization to solve this?

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Absolutely! Since 10=2×5 10 = 2 \times 5 and 4=22 4 = 2^2 , you need two factors of 2 for divisibility by 4. But 10 only has one factor of 2, so not all multiples of 10 work!

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