Another classification can be made. The High and Low numbers make up the Outside numbers. 

These are the High Numbers.
1–012 013 015 017 018 019 023 024 025 026
2–027 028 034 035 036 037 038 045 046 047
3–048 049 056 058 059 068 078 079 089 123

These are the Middle Numbers.
4–124 125 126 127 128 129 134 136 137 138
5–139 146 148 149 157 158 159 167 168 169
6–178 179 189 234 236 237 238 246 248 249
7–256 257 258 259 267 268 269 278 345 346

These are the Low Numbers.
8–347 348 349 357 358 359 368 369 378 379
9–389 456 457 458 467 468 469 478 479 489
10-567 568 569 578 579 589 678 679 689 789