How many two digit numbers contain in digit 7?

There are 18 two-digit numbers that contain the digit 7. These numbers are: 17, 27, 37, 47, 57, 67, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 87, and 97. The digit 7 appears in the tens place for 70-79 and in the units place for the other numbers.