Investigate and explain the link between how numbers are recorded in modulus arithmetic and the units digit when the number is written in a different number base. Here is an example of a few randomly chosen numbers written as numbers modulo 7 and written in base 7). Investigate other number bases.
| Some numbers in base ten | 1 | 2 | 9 | 11 | 26 | 33 | 41 | 67 | 80 | 100 |
| The same numbers modulo 7 | 1 | 2 | 2 | 4 | 5 | 5 | 6 | 4 | 3 | 2 |
| The same numbers in base 7 | 1 | 2 | 12 | 14 | 35 | 45 | 56 | 124 | 143 | 202 |