Is it divisible by any higher number? Try divisibility by 15? No — $1 \cdot 3 \cdot 5 \cdot 7 = 105$, divisible by 15, but $3 \cdot 5 \cdot 7 \cdot 9 = 945$, also divisible by 15. But $5 \cdot 7 \cdot 9 \cdot 11 = 3465$, divisible by 5 and 3, but 5 and 7, but 3465 ÷ 15 = 231 — yes. But is it always divisible by $5$? No — try $7,9,11,13$: $7\cdot9\cdot11\cdot13 = 9009$, ends with 9 — not divisible by 5. So not always divisible by 5. - Groen Casting