How many of the numbers between 100 and 400 begin or end with 2? Explain.

I think it's 120 because u go 102, 112

, 122, 132 142 ... till you hit 192 then thats 10. then you start at 200 and you know that one hundred numbers are between 200 and 300 and they start with 2. so now you have 110. then you go 302, 312, 322, 332, 342, 352 ... and that 10 more so 110+10=120