Hands-on math!

Washington State Math Olympiad
Hints and Solutions
2012 Grade 8 Number Sense

Problem
1) Joey is playing a game where winning means getting the biggest product. He rolls a 6 sided die 5 times getting the numbers 1, 3, 4, 5, 6. He creates a 3 digit number and a 2 digit number using each digit once. He wins if the product of his two numbers is bigger than the products of his competitors. What should his 3 digit number be?

2) Initially on Michael's hands there are 3.9 x 106 bacteria. He sprays his hands with a hand sanitizer, killing 99.5% of them. He then washes his hands twice, removing 10% of the remaining bacteria each time. How many bacteria are left? Express your answer in scientific notation.

3) The expression represented by the boxes is the quotient of a 2-digit number raised to an exponent by a 2-digit number raised to an exponent. Each box represents a digit from the list 1, 2, 3, 4, 5, and 6 with no repeats. To make the resulting quotient as small as possible what is the second 2-digit number represented by the fourth and fifth box?

Problem
4) What is the difference between the average of all integers from -100 to 101 and the average of all integers from -500 to 501?

5) What is the smallest whole number k > 0 so that
?