Question

The number of six digits numbers in which digits are in ascending order must be

• A. $48$
• B. $84$
• C. $120$
• D. $126$

Answer 1

The correct option is B $84$

Solution-

six digit number in which

digit are in ascending order.

select 6 digit out of 9

then there is only are way to

average it in ascending order

Total ways ${=}^9{C}_6=\frac{9\times 5\times 7\times 6!}{3!6!}=\frac{9\times 8\times 7}{3\times 2}$

$=84$

B is correct.