Page 116 - Numbertheory

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:( ) 5
.n

5, 10, 15, 20, 25, 30, 35

25 5

n = 35 58 35 ! .
.

3!× 5! × 7! [MAC10A 2005] ( )

6( ) 5( ) 4( ) 3 ()

:( )

3! × 5! × 7! = 28 × 34 × 52 × 71
3!×5!× 7!

a≤8 3 2a × 3b × 5c × 7d

a ∈{0, 3, 6} dcba

. d ≤1 c ≤2 b ≤4
.d ∈{0} c ∈{0} b ∈{0, 3}

3!×5!× 7!

. 3× 2×1×1 = 6

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