Suppose all nine points are used. If it is a single digit, 1 single digit, if it is a double digit, nine double digits, if it is a three digit, 1+2+3+4+5+6+7+8+9=45, so it can be arranged into 45 three digits. If it is four digits, 9 *1+8 * 2+7 * 3+6 * 4+5 * 4 * 6+3 * 7+2 * 8+1* 9 =195.

It can be arranged in four digits: 195.