The greatest number of four digits which is divisible by 21, 25, 40 and 75 is:  Choose the correct choice from the following.
A) 9000  B) 8400  C) 9600  D) 9800  E) 9200
Greatest number of 4-digits is 9999.   L.C.M. of 21, 25, 40 and 75 is 4200.   On dividing 9999 by 4200, the remainder is 1599.   Required number  (9999 - 1599)= 
<gadget id="calculator"> (9999 - 1599)</gadget>
<output>8_400</output>
8400.   Answer: Option 8400
<result>B</result>
The greatest number of four digits which is divisible by 21, 25, 40 and 75 is: