2 ms·

I'm a bit surprised - I do almost all these things in my head anyway, never thought them as tricks just that I'm weird and cannot model school methods like othe

• LordKano 10y ago
  I thought pretty much the same thing as I was reading this. I don't think of these as "tricks", just "how I do it in my head".
• irrational 10y ago
  But, how did you learn them? I didn't do many of these things naturally, but I've read about them over the years and have learned to do them from reading so now I do almost all these things in my head too.
  • george_ciobanu 10y ago
    Laziness? I didn't like remembering to carry when multiplying 45x16 so I did 40x16 + 5x16 - easy to add two numbers in your head, hard to remember two shifted partial results (the way it's done on paper). Different media require different methods. 45x 16 on paper: 270+ 45 It's easy to see here but in your head you have to remember that 45 is shifted left when added to 270. Visually it makes sense but otherwise hard. Breaking things into multiplications by 10, five or other easy substeps is recursive and easy to trace back up. Truth is I don't know how I came up with it, I think I was just lazy.