Compute in the most rational way. 1) 12∙43+43∙88 2) 23∙77+77∙77 3) 45∙123−45∙80+45∙57 4) 1341∙12−12∙1241

Solving the questions below we use PEMDAS
that is:
parenthesis, exponential, multiplication, division, addition then lastly subtraction.
1) 12×43+43×88
In this situation we begin by multiplication first:
516+3784
Next we add the result
4300

2)23×77+77×77
we multiply first
1771+5929
next we add them
7700

3) 3) 45∙123−45∙80+45∙57
We multiply first 
5535-3600+2565
next we add the positive numbers then lastly we subtract the results
8100-3600
subtracting gives us:
4500

4)1341×12−12×1241
First we multiply the numbers
16092-14892
next we subtract:
1200