Question

Write all possible two digit number that can be formed by using the 3, 7 and 9 if the repetition of the digit is allowed​

Answer 1

Answer:

The ten's place can be filled in 3 ways; and for each of the ways, the unit's place can be filled in 3 ways.

. So, there will be 3*3 = 9 numbers

These are: 33, 35, 37, 53, 55, 57, 73, 75 and 77.

Answer 2

Answer:

We know that a two-digit number has two places.

The ten’s position can be occupied in three different ways and for every way, the unit’s position can be occupied in three ways.

Case 1: Consider the digits 3 and 7 then possible numbers are

33, 37, 73 and 77

Case 2: Consider the digits 3 and 9 then possible numbers are

39, 93 and 99

Case 3: Consider the numbers 7 and 9 then the possible numbers are

79 and 97

So, there will be 3 X 3 = 9 numbers and those numbers are

33, 37, 39, 73, 77, 79,  93, 97, 99.

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