Question

exact 4. Determine the greatest 5-digit number which is exactly divisible by each of 8, 15 and 21.
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Answer 1

Answer:

Largest five digit number is 99999,

LCM of 7,10,15,21,28 is 

7=7

10=2∗5

15=3∗5

21=3∗7

28=2∗2∗

so, 2∗2∗3∗5∗7=420

⇒42099999

remainder will be 39 so 

99999−39=99960