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The greatest 4-digit number exactly divisible by 5, 15, 20 is
- A9990
- B9960
- C9980
- D9975
Answer not set
Discussion 1
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CCommunity
To be divisible by all three of 5, 15 and 20, the number must be divisible by LCM of 5, 15 and 20
LCM of 5, 15 and 20 is 60 (= 2 × 3 × 2 × 5).
Thus, the number must be a multiple of 60.
⇒ 9999/60 = 166.65
∴ Largest multiple of 60 less than 9999 is: 60 × 166 = 9960
Hence, 9960 is the answer.
LCM of 5, 15 and 20 is 60 (= 2 × 3 × 2 × 5).
Thus, the number must be a multiple of 60.
⇒ 9999/60 = 166.65
∴ Largest multiple of 60 less than 9999 is: 60 × 166 = 9960
Hence, 9960 is the answer.