Hands-on math!

Washington State Math Olympiad
Hints and Solutions
2010 Grade 8 Number Sense
Problem
1) At Bob's school the price of school t-shirts goes up by 10% rounded to the nearest cent each year. This year the price of the t-shirt is $10. What will the price be 4 years later?
2)In Kyle's English class 4 students have green eyes. 5/8 of the students have brown eyes and 1/4 of the students have blue eyes. There are no other eye colors. How many students are in his class?

3) On a number line, what fraction is halfway between 1⁄3 - -3⁄4 and -3⁄8 - 5⁄6?

Problem
4) Liz was playing with a pile of pennies. She noticed when she stacked them in piles of three there was 1 left over. When she stacked them in piles of five there were 2 left over. When she stacked them in piles of seven there were 3 left over. What is the smallest number of pennies she could have?

5) How many perfect square numbers will there be in the first century of the third millennium, so between 2000 and 2100? List them.