Calculation rules

Japanese school year: Elementary 4

What you learn

Use the associative and distributive laws to calculate smartly.

Key points

Multiplying a sum (b + c) by a gives the same answer as multiplying each by a and adding.

a \times (b + c) = a \times b + a \times c

Multiplying a difference (b - c) by a gives the same answer as multiplying each by a and subtracting.

a \times (b - c) = a \times b - a \times c

When multiplying three numbers, doing a × b first or b × c first gives the exact same result.

(a \times b) \times c = a \times (b \times c)

When adding three numbers, doing a + b first or b + c first gives the exact same result.

(a + b) + c = a + (b + c)

Choose a set to practice.