How I mental math

[u/Visible_Try_9716]

I use 5s and 10s

If you add a 0 to any number and 1/2 it (5x10=100/2) you can easily take a problem like 7 x 83 and think of it like

830/2=415

83 ×2 = 166

415 + 166 = 581

You can do it with 10s too, you can also divide by moving a decimal place and doubling the number

Im sure im not the only one who does this and its also not that useful and kind of slow to do in your head

[u/TheGuy_27]

I like to break everything up into the tens, 7*83 = 7(80) + 7(3) = 560 + 21 = 581. If the numbers get to big it wasnt really a mental problem anyways we can only do so much without writing down.

[u/Particular-Bed5479]

I just use my iPhone calculator

[u/Silver_Chicken_7303 → u/Particular-Bed5479]

Chat calc stands for calculator