Doubling 2-digit numbers and halving 3-digit numbers mentally.

Some people like to start doubling with the units, others like to start with the tens. It doesn?t matter as long as the method is fast and accurate.

More work on doubling and halving, including larger numbers and fractions.

Some people (especially those who still use feet and inches!!) think it is important to know how to multiply by 12. It?s easy ? just add 10 times the number to 2 times the number.