Question

How many two digit numbers have the digit 7 only once

Answer 1

there are 18 2-digit numbers with the digit 7 only once.

Answer 2

There are 17 two digit numbers have the digit 7 only once.

Explanation:

We're considering the numbers from 10-99.

1. 17

2. 27

3. 37

4. 47

5. 57

6. 67

7. Nope

7. 87

8. 97

AND 70, 71, 72,73, 74, 75, 76, SKIP, 78, 79

8 numbers end with a seven. And 9 numbers start with a seven. We toss 77 out bc it has two sevens in it.

There are 17 two digit numbers that have the digit 7 only once.