Prof. Andrew Stapleton at U. of Wisconsin-La Crosse shares with us a fun teaching tip.
Kick off your class with this captivating two-minute math trick!
Step 1: Grab a calculator. Ask everyone to take out their calculator or open the calculator app on their phone.
Step 2: Create a six-digit number. Instruct each student to think of any three-digit number and repeat it to form a six-digit number. For example: 729 becomes 729729.
Step 3: The magical prediction. Invite students to shout out their six-digit numbers all at once. Pretend you’re calculating each one in real-time and confidently declare:
“I am going to calculate quickly and give you three directions and you will never have a remainder. That is, each iteration you will have a whole number. Follow my instructions, and your final result will always be your original three-digit number!”
Step 4: The steps.
Have everyone perform these operations on their six-digit number:
Divide the number by 13 (they’ll get a whole number).
Divide the result by 11 (still a whole number).
Divide that result by 7.
Surprise! Each student ends up with their original three-digit number.
How does it work?
The math is straightforward but seems like magic:
The real fun? Your dramatic prediction adds flair and mystery, making the trick seem far more complex than it is. Enjoy the “wow” moment as your students are amazed!