We liked the solutions from Jake and Polly of
West Flegg Middle School, Great Yarmouth.
NRICH can change to RNICH, RNCIH, RNIHC, NIRCH, NIRHC, NRCIH and
NRIHC.
A peal of bells in which the 24 permutations of 4 bells are rung
once each is given by
1234
2143
2413
4231
4321
3412
3142
1324
3124
1342
1432
4123
4213
2431
2341
3214
2314
3241
3421
4312
4132
1423
1243
2134
1234