Activities & Lessons

# Challenge Your Students with These 100th Day of School Math Activities

The 100th Day of School is just around the corner!

Historically, the reason why 100 seems so important is simply because humans typically have 10 fingers, and 10 times 10 is 100. This anatomical accident has made the number 100 important, both in and out of the math classroom.

What better way to celebrate than with some puzzles about the number 100? The puzzles below give students a fun way to practice operations with whole numbers through 100. They rely on recognizing ways to make multiples of 10 (for example, spotting that 27 and 23 add to 50) and discovering strategies to make 100 (for example, trying to reduce an expression to 25 × 4).

The puzzles are appropriate for students in second grade and older. The challenge puzzles, which require knowledge of fractions and division, are better suited for students in fifth grade and older. In particular, the puzzles practice these standards:

• 2.NBT.5 (Fluently add and subtract within 100)
• 5.NBT.7 (Perform operations with whole numbers and decimals through 100)

Overall, these 100th Day of School math activities will stretch the brains of students of all ages, including adults!

Once students have completed the 100th Day of School math printables, you can share these fun facts with them about the number 100!

• The fact that we have 100 U.S. senators has nothing to do with the number of fingers on our hands. It’s because there are 50 states and two senators per state!
• 100 is the basis for the idea of a percent. Percent comes from per centum, or per hundred, in Latin.
• Also coming from the Latin word centum, C is the Roman numeral for 100.
• On Rosh Hashanah, the Jewish New Year, many rabbis blow the shofar (an ancient musical instrument made from a ram’s horn) 100 times.
• 100 has the unusual property that it can be written as ab+ ba. Can you figure out a and b? (See the end of this post for the solution.)
• Want to hear some unusual connections to prime numbers? The sum of the first nine prime numbers is 100. Even more strangely, there are exactly 100 prime numbers whose digits are in strictly ascending order (for example, 349 counts because it’s prime and 3 < 4 < 9).
• In the U.S., we dial the phone number 9-1-1 when we need immediate help. However, in Greece, India, Israel, and Nepal, people dial 1-0-0 for police, and in Belgium, people dial 1-0-0 for an ambulance or firefighter.
• In 2014, the CW produced a TV show called The 100. In the show, a nuclear apocalypse destroys almost all life on Earth. In an attempt to see if life on Earth is still possible, humans who are living in space send 100 juvenile detainees to try and live on the planet.
• On March 2, 1962, Wilt Chamberlain set a record for the highest number of points scored in one NBA game by a single player—100.
• There are 100 tiles in a standard English Scrabble set. Want to quickly check if your Scrabble set has all the tiles? Tournament players group them into four sets of 5 × 5 tiles. That way before beginning a game, both players can easily see that there are 4 × 25, or 100, tiles.

Solution: 26 + 62 = 100.

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For more ways to celebrate the 100th Day of School with your students:

This blog, originally published in January 2020, has been updated for 2021.