Base conversion mathematical tool for hexadecimal and binary

[KRSplat]

-It's very difficult to convert numbers in base 16 (hexadecimal) and in base 2 (binary),
is there a tool or a math device that would allow this to be done more quickly?

For example:

1F (base 16) = 31 (base 10)
11111 (base 2) = 31 (base 10)

11 (base 16) = 17 (base 10)
10001 (base 2) = 17 (base 10)

10101 (base 2) = 21 (base 10)
15 (base 16) = 21 (base 10)

10011 (base 2) = 19 (base 10)
13 (base 16) = 19 (base 10)

¿How could base conversions be more simplifyed, mathematically?