The Language of Mathematics (8): Multiplying and Dividing

[Thaperfect1]

I've just been accepted at uni and i can't even do division :( As part of my condtional offer i must pass my maths exam to be able to do the degree next year. Im tryin to enjoy maths but im finding it really hard. Im struggling so much with this part :( Just need to keep trying harder. :(

[2JROLLn]

I just want to say thank you for your videos you have made math less fear full.

[chychochycho]

my pleasure, I'm glad to help :)

[CHRISTMASBASTARD]

I love your open approach... we need to stop following stereotypes cuz its killing us. My technique to adding and subtracting any number over 10 which I learnt from using a soroban is: x±y=z, 10-y=a, x±10±a=z, if y is -y then 10 is -10 and a is +a and if y is +y then you have the opposite. i.e. 7+8, 10-8=2 , 7+8=7+10-2=15. i.e 17-9, 10-9=1, 17-9=17-10+1=8.

[talkotime]

one thing I always found frustrating as kid is that they always referred to carrying the ten as carrying the one. I never understood how a ten could just magically turn into a one.

[mmille10]

Corrections: In the multiply by tens part I should have said: "but if a result is more than 99, you carry". To explain "the zero placeholder" one could say, "since we're not going to be getting any ones out of this multiplication, we'll go ahead and put a zero here."

[mmille10]

In the 25 x 12 example, it would really be better if you made place value explicit in the method. You multiply and then you add to make the first line result: 2 x 5 = 10 (just leave a zero placeholder in the ones place), 2 x *20* + *10* (from the carry) = 50. Now you start multiplying by tens, but if a result is more than 100, you carry. So you put a 0 in the ones place as a placeholder in the second line result:, and then *10* x 5 = 50, 10 x *20* = 200. 200 + 50 = 250. Now add the two lines.

[k1ngross]

Very good, this one went a little fast I feel though. Maybe a little more explanation on why you start adding and subtracting stuff would have been helpful.

Thankfully this is a video and I could watch it a couple times to get it in my head :D

Thanks

[bodhidarma1]

Ughh. You lost me as a fan on this one. People need to stop learning to do basic operations by working right to left on paper, or at least less emphasis should be placed on it. Seriously, try using this method in your head to add two three digit numbers together and you'll quickly realize its limited worth.

Math teachers, stop doing this!

Teach it the right way. Left to right, done in steps. It makes head math a hundred times easier.

[chychochycho]

you should start making videos and teaching it the other way.

[bodhidarma1]

I'm not a math teacher.

You're a Good math teacher, so YOU should do it, help to rid humanity of this DINOSAUR of an operations method. You encourage the discarding of calculators, but working it out on paper in this fashion is almost just as bad!

232 + 124 for example... break 232 down into 200 + 30 + 2 and add these on piece at a time to 124.

If you're doing it in your head, thinkin, carry the this, carry the that, your head gets discombobulated. Takes too long.

Read Math Magic.

[bodhidarma1]

Btw, what you did with that wall chalk in the first few videos... and the measurements, and knowing where to point the chalk... it was an awesome demonstration of the power of mathematics. I'm still left wondering how you did it exactly.

[chychochycho]

hehe, i was looking at a very small screen :)

but i like the math explanation more :))

[SF4Player]

Thank you Chycho my long division has improved I knew how to do it but I would end at the last number and did not know the decimal trick.

-Thomas.

[neltito15]

it was really easy to understand with u thanks

[Randz88Goddex]

People must walk by and be like wtf there math all over my building! lol

really tho i luv these videos your teaching me alot more even about the basics then i learned in school makes sense and is fun too.

Thank you.

[chychochycho]

your welcome, and i personally believe that the basics is what's been missing from our education system, which is why i'm doing this.

Once the basics are understood then everything else comes together.

[DeWittAlbright]

Really good work and you make it really interesting.

I love the concept.

[Flamtapa]

What a Fantasic idea! thankyou!

[dantheman163]

cool