EXERCISE

How many four-digit numbers are there in all?

How many $8$-digit numbers are there in all?

Write $10075302$ in words and rearrange the digits to get the smallest and the largest numbers.

What is the smallest $3$-digit number with unique digits?

What is the largest $5$-digit number with unique digits?

Write the smallest $3$-digit number which does not change if the digits are written in reverse order.

Find the difference between the number $279$ and that obtained on reversing its digits.

Form the largest and smallest $4$-digit numbers using each of digits $7, 1, 0, 5$ only once.