A three-digit number is to be formed from the digits 0, 1, 3, 5, 6.

(i) When repetition of digits is allowed, 100’s place digit should be a non-zero number.

Hence, it can be anyone from digits 1, 3, 5,6.

∴ 100’s place digit can be selected in 4 ways.

10’s and unit’s place digit can be zero and digits can be repeated.

∴ 10’s place digit can be selected in 5 ways and the unit’s place digit can be selected in 5 ways.

∴ By using the fundamental principle of multiplication,

the total number of three-digit numbers = 4 × 5 × 5 = 100

(ii) When repetition of digits is not allowed, 100’s place digit should be a non-zero number.

Hence, it can be anyone from digits 1, 3, 5, 6.

∴ 100’s place digit can be selected in 4 ways. 10’s and unit’s place digit can be zero and digits can’t be repeated.

∴ 10’s place digit can be selected in 4 ways and the unit’s place digit can be selected in 3 ways.

∴ By using the fundamental principle of multiplication,

the total number of two-digit numbers = 4 × 4 × 3 = 48