Dot Division Method

[phillip1882]

http://thescienceexplorer.com/universe/use-quick-trick-speed-long-division

can someone show me what 975 / 15 would look like?

 

[GAHD]

That's a new one to me. I'd just use a combination of known tricks to simplify as I do it mentall, getting 65.

Both divisible by 3 becomes 325 (9/3=3 and 75/3=25) / 5 (15/3=5)

-> anything divided by 5 = double it and shift the decimal point (325*2=650, shift = 65)

I guess the line thing could be as useful as imagining a mental abacus if you get used to it?

[exchemist]

Yes the example quoted in the OP is a bad one, since it is obvious that 975 is divisible by both 3 (digits add up to 21, which is divisible by 3 )and 5 (ends in 5 or 0). So long division isn't needed at all.

 

This method of division is an interesting curiosity but, looking at the example they choose,  145824/112, it seems to me that ordinary long division will be as fast as drawing dots and joining them up with lines. The second example they pick is even worse.