@AstroHyde Yes, a mechanical calculator. I don't recognize that one but it looks similar to a Monroe-Matic that I used back in the last century.
It's 1964 and you need to multiply two 4-digit numbers, and do it lots of times? Slide-rule gets you to 3 decimal places. Your book of log tables might help, but it's still slow. What if you want full accuracy? Do it longhand?
Use one of these. Chunka, chunka, chunka, chunka, chunk: answer.