Question

Find the greatest number which will divide the greatest 4-digit number and the greatest 5-digit number exactly.

• A. 9
• B. 8
• C. 7
• D. 3
• E. none

Answer 1

The correct option is A 9

The greatest $4$ digit Number is $9999$

The greatest $5$ digit Number is $99999$

The Factors of $9999$ are $3\times 3\times 11\times 101$

The Factors of $99999$ are $3\times 3\times 41\times 271$

The $\text{HCF}$ is given by $3\times 3=9$