Andrew decorated 20 biscuits to take to a party. He lined them up and put icing on every second biscuit and different decorations on other biscuits. How many biscuits weren't decorated?
What Could It Be?
Age 5 to 7 Challenge Level
Pick any number to start with and put it in the box. Then complete the calculation.
Then try a different number. Make sure you complete the calculation each time.