In many courses of study the order of systematic formation of the multiplication table bonds is: 1 × 1, 2 × 1, etc., 1 × 2, 2 × 2, etc., 1 × 3, 2 × 3, etc., 1 × 9, 2 × 9, etc. This is probably wrong in two respects. There is abundant reason to believe that the × 5s should be learned first, since they are easier to learn than the 1s or the 2s, and give the idea of multiplying more emphatically and clearly. There is also abundant reason to believe that the 1 × 5, 1 × 2, 1 × 3, etc., should be put very late--after at least three or four tables are learned, since the question "What is 1 times 2?" (or 3 or 5) is unnecessary until we come to multiplication of two- and three-place numbers, seems a foolish question until then, and obscures the notion of multiplication if put early. Also the facts are best learned once for all as the habits "1 times _k_ is the same as _k_," and "_k_ times 1 is the same as _k_."[8] [8] The very early learning of 2 × 2, 2 × 3, 3 × 2, 2 × 4, 4 × 2, 3 × 3, and perhaps a few more multiplications is not considered here. It is advisable. The treatment of 0 × 0, 0 × 1, 1 × 0, etc., is not considered here. It is probably best to defer the '× 0' bonds until after all the others are formed and are being used in short multiplication, and to form them in close connection with their use in short multiplication. The '0 ×' bonds may well be deferred until they are needed in 'long' multiplication, 0 × 0 coming last of all. In another connection it was recommended that the divisions to 81 ÷ 9 be learned by selective thinking or reasoning from the multiplications. This determines the order of bonds so far as to place the formation of the division bonds soon after the learning of the multiplications. For other reasons it is well to make the proximity close.