Question

The number of ways iin which a seven digit number with sum of digits $36$ can be formed with digits $1,2,3,4,5,6,7,8,9$ (no repetition) is:

• A. $7!$
• B. ${}^9{P}_7$
• C. $3(7!)$
• D. $4(7!)$

Answer 1

The correct option is D $4(7!)$

Co-ordinations can be$⟶2,3,4,5,6,7,9⟶1,3,4,5,6,8,9⟶1,2,3,6,7,8,9⟶1,2,4,5,7,8,9$

So, number of co-ordinations $=5\times 7!$