Solving large multiplications in my head What would be the best approach to solve 73 x 42 in my head?
I started with 70 x 40 and then 3 x 40 and combined, but at this point I forgot what I had done and ended up getting lost and not figuring it out.
Is there a good method for solving multiplication as such in my head?

I would double $73$ to get $146$, and then double it again to get $292$. I take advantage of the fact that doubling a number in your head is relatively easy since you only have to remember one number at a time. Then I would multiply that result by ten to get $2920$. This is $73\times 40$. Now I just need to add $2\times 73$, which we already calculated as $146$. Adding, we get $2920+146=3066$.
