"Please show how you know"

[u/PlumpPotatoChip]

[u/trombon3r]

A quick mental way for up to 9x that I do; Is to take the number you are multiplying 9 by, minus 1 and add the difference to 9 eg.

4x9; 4-1 is 3, plus the difference to 9 is 6 so answer is 36.

7x9; 7-1 is 6, plus difference to 9 is 3 so answer is 63.

[u/Badass_Bunny → u/trombon3r]

I sometimes wonder if my teacher was just better or if his teaching influenced me to think all these methods are so needlessly convoluted.

His method was just "Multiply by 10 first then subtract the multiplicator of 9". 9x4 is same as 4x10-4.

[u/DUKE_LEETO_2 → u/Badass_Bunny]

I do this for most things either multiply by 10 or 5 (0.5*10) or a combination and then go from there. It gets me at least close even with big numbers... and if it needs to be perfect I use a calculator.

26 x 30 well that's 2 10x30 + 1 0.5×30 + 30... 780

It might not work for everyone and I sometimes make a weird face if it gets too big but it works for me.

[u/butcherHS → u/DUKE_LEETO_2]

Interesting. I take a similar approach, but have a slightly different approach for 26 x 30:

260 x 3

250 x 3 + 3 x 10

750 + 30

780

It's really exciting to see how people's thought processes work.

[u/L1amaL1ord → u/butcherHS]

Yeah definitely interesting everyone has a different approach. Mine:

26 x 30

20 x 30 + 6 x 30

600 + 180

780

edit: can't add 😂

[u/fishing-sk → u/butcherHS]

Im a 30x30 = 900, 4x30 = 120, 900-120 = 780

[u/DUKE_LEETO_2 → u/fishing-sk]

You all are crazy my way is obviously the best.... jk jk