Google Spreadsheets, how to get sum of products of pairs from ranges?

Question

Google Sheets

An example that shows my way of "manual" multiplication of each pair and the final summation:

In fact, it has many pairs and blocks.
Is it possible to somehow multiply pairs of two or more ranges to get the required result?

Answer 1

https://docs.google.com/spreadsheets/d/1UZLG1Q9OQp...

Answer 2

But you simply cannot calculate the product of rows (A1*B1=C1), and then calculate the sum of column C.