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AQA GCSE · Question 04.2 · Number
Mica says, "When two multiples of 5 are added, the answer is always a multiple of 10". Give one example to show that he is wrong.
Mica says, "When two multiples of 5 are added, the answer is always a multiple of 10". Give one example to show that he is wrong.
How to approach this question
1. Choose two multiples of 5. For example, 5 and 10.
2. Add them together: 5 + 10 = 15.
3. Check if the result is a multiple of 10. A multiple of 10 must end in a 0.
4. 15 does not end in a 0, so it is not a multiple of 10.
5. This example shows that Mica is wrong.
Full Answer
An example such as 5 + 10 = 15. 15 is not a multiple of 10.
A multiple of 5 is any number that can be divided by 5 exactly (i.e., it ends in a 5 or a 0). Examples: 5, 10, 15, 20, 25...
A multiple of 10 is any number that can be divided by 10 exactly (i.e., it ends in a 0). Examples: 10, 20, 30, 40...
Mica's statement is that the sum of two multiples of 5 is always a multiple of 10. To prove him wrong, we need a counter-example.
Let's try adding two multiples of 5:
- Example 1: 10 + 20 = 30. This is a multiple of 10. This supports his statement.
- Example 2: 5 + 15 = 20. This is a multiple of 10. This also supports his statement.
- Example 3: 5 + 10 = 15. This is NOT a multiple of 10. This disproves his statement.
Any example where the sum ends in a 5 will work.
Common mistakes
✗ Providing an example that works (e.g., 10 + 10 = 20).\n✗ Just stating "he is wrong" without giving a numerical example.
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