tnutty

1. The problem statement, all variables and given/known data

convert (352416)_7 to (...)_3

the _7 means base 7 and similarly, _3 means base 3.

Idea : convert base 7 to base 10 then base 10 to base 3.

I know I can use expansion, 3 * 7^6 + 5 * 7^6 ... to convert it to base 10.

but in my exam, we are not allowed to use calculators, and I really not want to spend time
on figuring out the power of X. So do you know a faster way to convert this to base 10?
From then on I could convert it to base 3.