Class 3 — Mathematics
Multiplication: Understanding Tables and 2-digit by 1-digit Products
Class 3
- ✓To understand multiplication as a form of repeated addition.
- ✓To memorise and recall multiplication tables up to 10.
- ✓To multiply a 2-digit number by a 1-digit number without regrouping.
- ✓To multiply a 2-digit number by a 1-digit number with regrouping (carrying over).
- ✓To solve simple daily life problems involving multiplication.
Key concepts
Multiplication is a quick way of doing repeated addition. For example, if you have 3 groups of 4 apples each, you can add 4 + 4 + 4 = 12. Or, you can multiply 3 × 4 = 12. The symbol '×' means 'multiplied by'.
Multiplication tables are very important for quick calculations. You must memorise tables from 1 to 10 thoroughly. Knowing your tables will help you solve multiplication problems much faster.
In a multiplication sum, the number being multiplied is called the multiplicand. The number by which we multiply is called the multiplier. The answer we get after multiplication is called the product. For example, in 5 × 3 = 15, 5 is the multiplicand, 3 is the multiplier, and 15 is the product.
To multiply a 2-digit number by a 1-digit number, we write the numbers in columns (Tens and Ones). First, multiply the 1-digit number by the digit in the Ones place of the 2-digit number. Then, multiply the 1-digit number by the digit in the Tens place. Write the products in their respective places.
When the product of the Ones place multiplication is 10 or more, we need to regroup. We write the digit in the Ones place of the product and carry over the digit in the Tens place to the Tens column. Then, we multiply the 1-digit number by the digit in the Tens place of the 2-digit number and add the carried-over number to this product.
Key facts to remember
- 1Multiplication is a shortcut for repeated addition.
- 2Any number multiplied by 0 gives 0 as the product (e.g., 5 × 0 = 0).
- 3Any number multiplied by 1 gives the number itself as the product (e.g., 8 × 1 = 8).
- 4Changing the order of the numbers does not change the product (e.g., 3 × 4 = 4 × 3 = 12).
- 5Always start multiplying from the Ones place when using the column method.
- 6Memorising multiplication tables up to 10 is essential for quick and accurate calculations.
Worked examples
Example 1
Find the product of 7 × 5.
Answer
35
Memorising tables makes this much faster!
Example 2
Multiply 23 by 3.
Answer
69
Example 3
Multiply 47 by 2.
Answer
94
Remember to add the carried-over digit to the product of the next column.
Common mistakes
- ✗Not memorising multiplication tables, leading to slow and incorrect calculations.
- ✗Forgetting to carry over the Tens digit when the product of the Ones place is 10 or more.
- ✗Forgetting to add the carried-over digit to the product of the Tens place.
- ✗Multiplying the Tens digit first instead of starting from the Ones digit.
- ✗Incorrectly adding the carried-over number (e.g., adding it to the multiplicand's Tens digit before multiplying).
Exam tips
- ★Practise writing and reciting multiplication tables daily until you know them by heart.
- ★Always arrange numbers neatly in columns (Tens and Ones) for 2-digit by 1-digit multiplication.
- ★Be careful with regrouping (carrying over). Write the carried-over digit clearly above the next column.
- ★After solving, quickly check your answer, especially for sums involving regrouping.
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