Welcome to the Harrington Math Gym, a workout for Harrington Math Morning students and other curious students in grades 3-5. Check back often: materials are updated frequently. Want more? Visit our Archives or join us for Harrington School's Math Mornings and Family Math Nights.
_ "A man is not rewarded for having a brain, but for using it."
_ Have a friend write down any 5-digit number. Directly underneath it, you write another 5-digit number. Then they write another under that, then you write another, then they write another.
Tell them you know immediately what the sum of all five numbers is!
(Whenever it’s your turn, make sure that each digit in your number, when added to the digit above it, will total 9. To get the sum of all five numbers, subtract 2 from the last number your friend wrote, and put a 2 in front of the first digit of that answer.)
Can you figure out how that works?
What did the zero say to the eight?
_Challenging puzzles for Math Morning students and other curious and creative thinkers in grades 3 and up. This week: Tortoise and Hare
_Short movies and activities on various math topics. Many materials are free; others require a paid subscription. The site includes other subjects besides math, as well.
If you start with one single penny on January 1, and double the amount of money you have each day, on which day would you first have more than a dollar? On which day would you first have more than 100 dollars?
You might want to suggest this schedule to your parents for your allowance. They probably won't agree to it, though. By February 1st you would have more than 20 million dollars!