Question

How many natural numbers less than a million can be formed using the digits 0,7 and 8 ?

• A. $728$
• B. $729$
• C. $485$
• D. $486$

Answer 1

Answer: (A)

$728$

No. of $6$ digit numbers$=2\times 3\times 3\times 3\times 3\times 3$

$=486$

No. of $5$ digit numbers$=162$

No. of $4$ digit numbers$=54$

No. of $3$ digit numbers$=18$

No. of $2$ digit numbers$=6$

No. of $1$ digit numbers$=2$

$\therefore$Total no. of numbers$=486+162+54+18+6+2$

$=728$