41.   Jessica still got stuck on math problems, she said, but this time she had a teacher to call.

42.   Looking at that smudged sheet of elementary math problems, I could almost relate to that.

43.   Math problems came easily.

44.   Most of the children struggle to stay focused, take longer to understand complex thoughts and solve math problems, and tend to get excited easily.

45.   Nelson spends at least an hour each night going over math problems with Kristin.

46.   Or anyone who watched young mothers in Seoul quiz their children with math problems as they waited for the school bus.

47.   She read a lot of books, worked hard at math problems, listened to music and played with games that she had not looked at in two years.

48.   She is affectionately called the Math Machine because of her skills at solving math problems.

49.   She steps over younger children, who use candy for accounting to do math problems on the floor.

50.   So sophisticated in fact that one way of thinking about encryption is that it involves math problems that can be done forward but not backward.