Base 7 to Base 10

Base 7

In base 7, each digit position represents a power of 7: the rightmost digit counts individual ones, the next counts groups of 7, the next counts groups of 7×7, and so on — the same place-value idea as base 10, just with 7 distinct digits instead of ten.

Base 10

Base 10 works the same way: the rightmost digit counts ones, the next counts groups of 10, the next counts groups of 10×10, and so on, using 10 distinct digits.