Åk 6–9
 
English/فارسی

3.3 From addition to multiplication
You know that 3 · 5 = 15

What you really do is multiply the add five three times.

3 · 5 = 5 + 5 + 5 = 15



You know that 3 · 5 = 5 · 3?

5 · 3 = 3 + 3 + 3 + 3 + 3 = 15

In reality, multiplication is repeated addition.  If we calculate with addition each time we multiply, it would be slow and tedious.  Instead, we use the multiplication table and simplifications.