There are some techniques for calculating faster than calculator,so I want to know some of then like dividing and multiplying which are faster.
Here is a video of competition how small children do calculation faster.https://m.youtube.com/watch?v=7rkEg54HN4A
For example calculating this whitin 5 seconds or so…. $$\frac{296146931}{13873}$$
I'm sure you've heard of Arthur Benjamin but if you haven't look him up. He gave some tips on squaring numbers. So let's take something easy to square like 24. $24^2=(24+4)(24-4)+4^2$ by difference of squares and all. Now we can do 28*20+16 which is pretty easy. Another one is when the ones digits add up to 10 and the tens+ digits are the same. For example $12\cdot 18$ you add one to the tens digit and then multiply the ones digit and put them together so 216 is our answer. Another one is $19\cdot 11$ which is 209.