Why do this
This short challenge
presents children with the opportunity of
exploring number operations and practising mental arithmetic in a
What kind of number is $15$?
How will you remember what you have pressed?
What have you tried so far?
You could challenge children to explain how they would work
out, say $24 \times 37$ if a particular number on the calculator
was broken. How would they do it if the $2$ was broken? What about
if the $1$ and $2$ were broken etc.?
Having calculators to hand will allow learners to check their
ideas and they may need to be reminded to record the process in