# How do I work in #log_10# without a calculator?

##### 1 Answer

Aug 21, 2014

The best that you can do is to be precise with the order of magnitude unless you are able to memory the decimal values. You should know that

Recall that

If you want to get a good decimal value, you will have to memorize these values for the most significant digit:

1 - 0

2 - .30

3 - .48

4 - .60

5 - .70

6 - .78

7 - .85

8 - .90

9 - .95

So estimating:

#log 4783~~3.68# using mental linear interpolation between 4 and 5

#log 348734~~5.54# using mental linear interpolation between 3 and 4