Before a Calculator lesson as a starter I like getting learners to have fun with their resource. I get them to enter the following into their calculators and watch their amazement when they see the answer.
111,111,111 x 111,111,111 = 12,345,678,987,654,321
A great extension to this is asking the question “Why does this happen.?”
You can also start with 11*11 then 111*111 and so on and then ask learners to spot patterns predict 111 111 111* 111 111 111!!