Answer:
4 appears 55 times between 100 and 350
Explanation:
First lets compute the number of times 4 appear from 100 to 200
104, 114, 124, 134, 140, 141, 142, 143, 144, 145, 146, 147, 148, 149, 154, 164, 174, 184, 194
From 100 to 200: 4 appears 20 times ------- 1
Using the same method as above:
From 200 to 300: 4 appears 20 times ---------------2
From 300 to 350: 4 appears 15 times ---------------3
304, 314, 324, 334, 340, 341, 342, 343, 344 ( 2 times ), 345, 346, 347, 348, 349
From eq 1, 2 and 3
From 200 to 350: 4 appears : 20 + 20 + 15 = 55 times