1 + 1 = 2 and 1 + 2 = 3

Log in the base 10 of 100 is 2 -- this is the only log ya gotta know ;)  this is because 10 to the 2 power is 100
Then the log rules (that make no sense because they work off of exponent rules) follow.

log 10 + log 10 = log 100
1 + 1 = 2

log 10 + log 100 = log 1000
1 + 2 =3

It makes people laugh when they see that:

1 + 1 = 2 and

1 + 2 =3!! ;)