Speed Mathematics Simplified

We use the five combinations that add up to ten

the heavy concentration of pairs adding up to totals around ten

how the possibilities taper off toward high and low totals.

the order and pattern of this particular arrangement are especially instructive

most of us stumble most often.

The twenty combinations that add up to more than ten, incidentally, are also the twenty hardest to remember

Twenty add up to more than ten.

Five add up to ten.

of the forty-five combinations

twenty add up to less than ten.