1.99 multiplication table: Grade three students should master the multiplication table 99 in order to quickly calculate multiplication problems.
2. Allocation rate: When one number is to be multiplied by the sum of another number, we can allocate this number to each addend first and then calculate it. For example, 7 × (5+3) = 7 × 5+7 × 3.
3. Digital decomposition: decompose a large number into small numbers that are easy to calculate, and then multiply them. For example, 7 × 6 = 7 × (2+4) = 7 × 2+7 × 4.
4. Commutative law and associative law: According to commutative law and associative law, the calculation can be simplified by changing the order of multiplication. For example, 4 × 8 = 8 × 4, (2 × 3) × 4 = 2 × (3 × 4).
5. Inverse operation of numbers: If you know the inverse operation of a number, you can use it to simplify the multiplication operation. For example, 5 × 6 = 5 × 10 ÷ 2 ÷ 2 = 50 ÷ 4.
These methods can help junior three students do multiplication quickly. Practicing these skills and making them a daily habit will help improve math ability.