The product of any 4 consecutive integers must be divisible by _________ .
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This is a good start. However, your explanation has a slight gap.
Keep writing more solutions and you will get the hang of this!
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Sure Sir.I will soon include the proof of that statement in my answer when i get free.[Also the proof is so long(to write the generalization),so i'll write when i get free]
Out of the four numbers, two of the numbers are even. Of those two numbers exactly one is a multiple of 4. So 8 will divide their product.
We know product of 3 consecutive numbers is divisible by 8 , therefore
( x − 1 ) ( x ) ( x + 1 ) ≡ 0 m o d 8 ( x − 1 ) ( x ) ( x + 1 ) ( x + 2 ) ≡ 0 × ( x + 2 ) m o d 8 ∴ ( x − 1 ) ( x ) ( x + 1 ) ( x + 2 ) ≡ 0 m o d 8
The initial premise is only true if the first number is even. For example, 3x4x5=60, which is not divisible by 8.
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We use the fact that if a ∣ b and b ∣ c , then a ∣ c .
The product of any four consecutive integers is divisible by 4 ! = 2 4
So,let P be the product of the four consecutive integers,then: 8 ∣ 2 4 and 2 4 ∣ P .therefore, 8 ∣ P