convert the numeral to a numeral in base 10

14
5

3 answers

The "1" stands for 5 in base 5.

145
=(1*5)+4
=?
4.5 + 1.1
20 + 1

21
Your working is for
415
=4.5 + 1.1
=20 + 1
=21

The units digit is multiplied by 1, and the second digit from the right is multiplied by the base, 5 in this case.
If the number has more than 2 digits, the next digits (to the left) are multiplied by the subsequent powers of the base.

Example:

3217
=3*7^2 + 2*7^1 + 1*7^0
=3*49 + 2*7 + 1*1
=147 + 14 + 1
=162

So
415
=4*5^1 + 1*5^0
=4*5 + 1*1
=21