1.
Write all possible numbers using the digits 3,6 and 8 without repeating of digits.
Solution:

The numbers are: 3 at unit place: 863,683Hint: keep 3 at unit place and interchange the position of 8 and 6 6 at unit place:836, 386 Hint: keep 6 at unit place and interchange the position of 8 and 3 8 at unit place:638,368 Hint: keep 8 at unit place and interchange the position of 6 and 3 Question: Do it yourself for 2,4 and 9 2. How many whole numbers have two digits. Solution: The two digits whole numbers are from 10 to 99. e.g. 10,11,12......99.

Therefore the two digit numbers= 99-(10-1)

=99-9

=90 Note:Its general formula is : For two digits number = two digits highest number-(two digits lowest number-1)

3. How many whole numbers have three digits. Solution: The two digits whole numbers are from 100 to 999. e.g. 100,101,102......999.

We will apply the same formula by changing the numbers of digits only.

Therefore the three digit numbers= 999-(100-1)

=999-99

=900

Used formula is :thre…

The numbers are: 3 at unit place: 863,683Hint: keep 3 at unit place and interchange the position of 8 and 6 6 at unit place:836, 386 Hint: keep 6 at unit place and interchange the position of 8 and 3 8 at unit place:638,368 Hint: keep 8 at unit place and interchange the position of 6 and 3 Question: Do it yourself for 2,4 and 9 2. How many whole numbers have two digits. Solution: The two digits whole numbers are from 10 to 99. e.g. 10,11,12......99.

Therefore the two digit numbers= 99-(10-1)

=99-9

=90 Note:Its general formula is : For two digits number = two digits highest number-(two digits lowest number-1)

3. How many whole numbers have three digits. Solution: The two digits whole numbers are from 100 to 999. e.g. 100,101,102......999.

We will apply the same formula by changing the numbers of digits only.

Therefore the three digit numbers= 999-(100-1)

=999-99

=900

Used formula is :thre…