Question

The number of five digit numbers having at least one of their digits repeated is

• A. $900$
• B. $1000$
• C. $62784$
• D. $2780$

Answer 1

Answer: (C)

$62784$

Total no. of digits formed with repetition $=9\times 10\times 10\times 10\times 10$
$=90000$

No of digits formed without repetition
$=9\times 9\times 8\times 7\times 6$
$=27216$

$\therefore$ Required no. of five digit numbers $=90000-27216=62784$