Alien Invaders


Posted by Perri Wilkinson | Posted in Addition, Place Value, Subtraction | Posted on August 28, 2017

This is a calculator warm up activity for place value, addition and subtraction.

Students begin by entering a 4 digit number into their calculator. These 4 digits are aliens coming down to earth. The students’ mission is to shoot them down in ascending order by subtracting the numbers one at a time.

For example:

  • A student’s number is 5271. They must first get rid of the 1 by subtracting 1. Leaving 5270.
  • They must then get rid of the 2 by subtracting 200. Leaving 5070.
  • Next they need to get rid of the 5 by subtracting 5000. Leaving 70.
  • The last step is to subtract 70. Leaving 0


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