One way to do this is to use long division in base 7.
To make it easier, we need multiples of 127 in base 7:
1×12=12
2×12=24
3×12=36
4×12=51 (4×2=7+1=117 so we carry 1; 4×1=4 plus carry = 51)
5×12=63 (5×2=7+3=137 so we carry 1; 5×1=5 plus carry = 63) or 51+12=63
6×12=105, that is, 63+12=105 (7 is 107)
146
12 ) 2115
- 12 (1×12)
61
- 51 (4×12)
105
- 105 (6×12)
0
ANSWER: 146 to base 7.
Another way is to convert to decimal: 12=7+2=9; 2115=2×343+49+7+5=686+61=747.
747/9=83=49+28+6=1467.