Basic Operations

Grade 7 Math - Basic Operations

Lesson Objectives

Perform addition of large numbers accurately.
Carry out subtraction with regrouping where necessary.
Multiply multi-digit numbers efficiently.
Divide large numbers and interpret remainders.

Lesson Introduction

Basic operations — addition, subtraction, multiplication, and division — are the foundation of all mathematical problem-solving. Whether you're calculating money, distance, or time, mastering these operations is essential.

Core Lesson Content

Addition: Putting numbers together to find the total.

Subtraction: Taking one number away from another to find the difference.

Multiplication: Repeated addition of the same number.

Division: Splitting a number into equal parts.

Worked Examples

Example 1: Add \(125,378 + 84,622\)
\(125,378 + 84,622 = 210,000\)
Explanation: Line up digits and add column by column.

Example 2: Subtract \(205,000 - 86,435\)
\(205,000 - 86,435 = 118,565\)
Explanation: Regroup where necessary and subtract each digit column.

Example 3: Multiply \(327 \times 46\)
\(327 \times 46 = 15,042\)
Explanation: Multiply step-by-step using long multiplication.

Example 4: Divide \(9,856 \div 4\)
\(9,856 \div 4 = 2,464\)
Explanation: Use long division method to divide digit by digit.

Example 5: Add \(678,945 + 223,711\)
\(678,945 + 223,711 = 902,656\)
Explanation: Start from rightmost digits and carry over where necessary.

Example 6: Subtract \(1,000,000 - 456,789\)
\(1,000,000 - 456,789 = 543,211\)
Explanation: Make sure to borrow across zeros carefully.

Example 7: Multiply \(123 \times 321\)
\(123 \times 321 = 39,483\)
Explanation: Multiply in parts: units, tens, hundreds, then sum.

Example 8: Divide \(10,000 \div 25\)
\(10,000 \div 25 = 400\)
Explanation: Estimate and divide step-by-step or simplify using factors.

Example 9: Add \(345,000 + 56,789\)
\(345,000 + 56,789 = 401,789\)
Explanation: Ensure digits are properly aligned before adding.

Example 10: Divide \(2,375 \div 6\)
\(2,375 \div 6 = 395 \text{ remainder } 5\)
Explanation: Use long division; remainder may be expressed as fraction or decimal.

Exercises

Find \(542,123 + 328,987\)
Subtract \(600,000 - 415,369\)
[JAMB] Multiply \(245 \times 38\) [Past Question]
Divide \(12,456 \div 4\)
[WAEC] Find \(789,654 + 110,111\) [Past Question]
Subtract \(999,999 - 654,321\)
Multiply \(89 \times 67\)
[NECO] Divide \(7,218 \div 9\) [Past Question]
What is \(111,111 + 222,222\)?
Evaluate \(84,000 - 29,999\)
Multiply \(305 \times 55\)
[NABTEC] Divide \(14,382 \div 3\) [Past Question]
What is \(999 \times 101\)?
Subtract \(800,000 - 123,456\)
Divide \(3,000 \div 12\)

Conclusion/Recap

Today, we reviewed how to confidently work with large numbers using basic operations. Being accurate with these operations lays the groundwork for solving more advanced math problems. In our next lesson, we’ll explore Fractions and Decimals.