1.1.4 · D1Arithmetic & Number Systems

Foundations — Multiplication — tables (1–20), long multiplication, area model

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This page builds, from absolute zero, every symbol and idea the parent note Multiplication topic leans on. Nothing here assumes you've seen the notation before. We go in order — each brick sits on the one below it.


1. The counting numbers and the "=" sign

Before we can multiply, we need the things we count with.

Figure — Multiplication — tables (1–20), long multiplication, area model

Look at the picture: both pans hold four dots. The bar is the level beam. Whenever you write , imagine that beam staying flat.


2. Addition and the "+" sign — the thing multiplication speeds up

Adding two piles is easy. Adding the same pile over and over () is where it gets slow — and slowness is exactly the problem multiplication solves. See Addition — carrying and place value for the carrying details we reuse later.


3. "Equal groups" — the picture multiplication is really about

Figure — Multiplication — tables (1–20), long multiplication, area model

4. The "" sign and the words factor and product


5. The grid picture and the "" arrow

To see why , we arrange the groups as a grid (a rectangle of dots).

Figure — Multiplication — tables (1–20), long multiplication, area model

6. Place value — what "" really means

This is the single most important brick for long multiplication.

Figure — Multiplication — tables (1–20), long multiplication, area model

Full details live in Place Value & Number Systems — but the box above is all the parent note needs.


7. The distributive law — "split, then add"

The engine of every multiplication method.


8. The multiplication symbols you'll also meet


The prerequisite map

Whole numbers 0 1 2 3

Equals sign as a balance

Addition plus combine piles

Equal groups same size piles

Multiplication a times b

Dot grid rectangle

Commutativity a times b = b times a

Place value 47 = 40 + 7

Times 10 shift left add a zero

Distributive law split then add

Long multiplication

Area model rectangle

Tables 1 to 20 learn half

Squares a times a

Division inverse

Read it upward: whole numbers feed addition, addition feeds equal groups, equal groups feed multiplication; place value plus the distributive law feed long multiplication and the area model.


Equipment checklist

Cover the right side and see if you can answer each before revealing.

What does the whole number set contain and exclude?
All counting amounts including zero; no fractions or negatives.
What does actually assert?
The two sides are the same amount — a balanced beam, not an instruction.
Write as repeated addition.
added to itself times ( copies of ).
Name the parts of .
and are factors; is the product.
Why does ?
One dot grid can be counted by rows or by columns — same dots, same total.
What does mean?
"Therefore / which forces" — the left proves the right.
Break into place value.
.
Why does append a zero?
Every digit shifts one column left, so its worth grows tenfold.
State the distributive law in words.
copies of = copies of plus copies of : .
Why is wrong?
must multiply every term inside the bracket, so it's .
What does mean and why "squared"?
; it's the area of a square of side .
What question does ask?
How many groups of make — the reverse of multiplication.

Connections

  • Parent topic — Multiplication
  • Addition — carrying and place value
  • Place Value & Number Systems
  • Distributive Law
  • Division — inverse of multiplication
  • Squares & Square Roots
  • Algebra — Expanding Brackets