problems E — fill 3-tile gap
| E-1: | 6 ~ x ~ y ~ z ~ | 7 (mod = | 8) |
| E-2: | 4 ~ x ~ y ~ z ~ | 1 (mod = | 7) |
| E-3: | 5 ~ x ~ y ~ z ~ | 2 (mod = | 9) |
| E-4: | 5 ~ x ~ y ~ z ~ | 2 (mod = | 10) |
| E-5: | 6 ~ x ~ y ~ z ~ | 2 (mod = | 10) |
| E-6: | 5 ~ x ~ y ~ z ~ | 5 (mod = | 6) |
| E-7: | 7 ~ x ~ y ~ z ~ | 7 (mod = | 12) |