Goals
Finding patterns in numbers
Practicing 3 and 4 digit subtraction
What To Do
First Explain the Process
Pick a 3 digit number, e.g. 268
Write the biggest number you can make with these digits, e.g. 862
Write the smallest number you can write with these digits, e.g. 268
Subtract the smaller number from the bigger number
Repeat steps 1.2-1.4.
Get each kid to pick their own 3 digit number and follow the steps described above
Ask them to repeat the process at least 4 times
Make a chart and write up all the results from each kid's number
Review the chart and get the kids to look for patterns
Repeat the steps 2-4 if necessary
Additional Work
Try the same process with a 4 digit number and even a 5 digit number. Note the results may not be the same in all these cases.
Background Information
Kaprekar's Constant - Wikipedia
Kaprekar's Constant - Numberphile Video