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Primary 4 | Maths
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how do i do this question?
Date Posted: 3 years ago
Views: 444
3 and 13 are both prime numbers (they have no other factors other than 1 and themselves)
So if a number is a multiple of both 3 and 13, it is also multiple of their product, which is 13 x 3 = 39
Only 39 can be the number since the original number is between 10 and 40.
We cannot have other multiples like 78 (39 x 2) , 117 (39 x 3) as they are too large. Subtracting 7 from them does not give a number between 10 and 40.
39 - 7 = 32
The original number is 32.
Check :
32 = 8 x 4
Or
32 ÷ 8 = 4
So it is a multiple of 8
So if a number is a multiple of both 3 and 13, it is also multiple of their product, which is 13 x 3 = 39
Only 39 can be the number since the original number is between 10 and 40.
We cannot have other multiples like 78 (39 x 2) , 117 (39 x 3) as they are too large. Subtracting 7 from them does not give a number between 10 and 40.
39 - 7 = 32
The original number is 32.
Check :
32 = 8 x 4
Or
32 ÷ 8 = 4
So it is a multiple of 8
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Hi! Hope this helps!
Date Posted:
3 years ago
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