Make the total 1 by entering a decimal. Don't forget to use a zero for the units and a decimal point. Optional printout of results after 10 questions.
These can be done by doubling the number half way between them - a useful technique to have 'up your sleeve'.
Add pairs of decimals 'in your head'. Printable results page after 10 questions.
Subtracting decimals mentally is pretty tough. It's often best to count up.
Just a minute to complete as many additions as possible.