Oh, sorry... 98.......198=49+2=51 multiples of two and 99.....198....33...66, 34 multiples of three. We have to subtract the multiples of 6, 102....198, 17..33, 33-16=17. 51+34-17=68.
I already found out that there are 51 multiples of two, but I didn't get how many multiples of three there were..