I came across lattice multiplication
a few years ago
Planning this video, I wondered...
I couldn't believe...
Let's try it out on this!
Draw a box first
Now we draw a line diagonally.
across each box, like this.
And we stretch it outside a bit.
Here we've got a ONES space...
a TENS space...
a space where we do our adding up.
Start multiplying at the right,
and work left.
2x7=14
3x7=21
And when we add,
we're NOT adding vertical columns.
We're adding diagonal strips instead!
In the ONES stripe...
we've got 4
In the TENS stripe...
1+1=2
And in the HUNDREDS... 2
It's 224
There's just something cool
about filling in those boxes
and adding up the diagonal stripes!
The thinking, and the math
just flows right along!
Check it out on this!
Set out the lattice
And now we multiply out.
2x5=10
2x6=12
1x5=5
No tens, just 5 ones
1x6=6
No tens, 6 ones.
3x5=15
3x6=18
Next, we add those diagonal stripes
Start on the right,
in the ONES stripe
Then...
5+1+2=
8
5+6+1=
Put the 2 here...
and carry the 1
Now, 8+1+1=10
Put down the 0
and carry the 1
1+1=2
And the answer is...
Check it on your calculator!
Give this method a go!
Before I go...
When I do that...
the digits end up
placed quite differently!
The products don't look the same AT ALL!
The numbers are lined up perfectly for adding
BUT...
I can't easily spot the products here.
They just don't jump out at me.
With a rectangular lattice instead...
the products are easy for ME to see.
The numbers are NOT set nicely for adding up...
But I will take that 'down-side'
because the multiplication is so clear!