Count all occurrences of digit 7 from 1 to 100: In units place (7, 17, 27, 37, 47, 57, 67, 77, 87, 97) = 10 times. In tens place (70, 71, 72, 73, 74, 75, 76, 77, 78, 79) = 10 times. Total = 10 + 10 = 20. Note: 77 contains two 7s and is counted in both groups.