halp

Quick review:

Here is how base 10 (decimal) (the one you are familiar with) works

3456₁₀        Each position is a power of 10    6 is is in the power 0 slot    10⁰ =1      so  6 x 1 = 6

                         5 is in the 10¹   slot    so   5 x 10¹  = 50

                            4 is in the 10²  slot      4 x 100 = 400

                                 3 is in the 10³   slot   so   3000                        added they equal  3000 + 400 + 50 + 6 = 3456

       there are 10 numbers that can be in each slot   0 through 9    for base 10

                  biggest  4 digit base 10 number would be 9999

Now here is a base 5 number     1234      numbers in the slots can be anything from 0-4   ( but not 5 ...or 6 or  7 or 8 or 9)

                                                       4 is in the 5⁰ slot    = 4 x 1 = 4

                                                            3 is in the 5¹   slot =   3 x 5 = 15

                                                                 2 is in the 5² slot  = 2 x 25 = 50

                                                                       1 is in the 5³ slot     1 x 125 = 125        added they equal   125 + 50 + 15 + 4 = 194₁₀

                                                                                 biggest four digit base 5 number would be  4444

                             so 1234₅   = 194_{10                        Clear as mud?}

Thanks EP.

These might also help   

https://www.youtube.com/watch?v=xkvRpwUrV6I

https://www.mathsisfun.com/numbers/bases.html