Basic Operation – JSS1 Mathematics Lesson Note (Second Term)

Basic operations are addition, subtraction, multiplication and division. To add or subtract, write the numbers under each other so that units, tens, hundreds and so on line up in columns, then work from the right. Multiplication and division of large numbers are also set out in steps, with each line of working written neatly.

Behavioural objectives

By the end of the lesson, students should be able to:

• Write numbers under each other according to their place values.
• Add and subtract large numbers, including word problems.
• Multiply large numbers, including word problems.
• Divide large numbers and state the quotient and the remainder.

How do you add and subtract numbers?

When adding or subtracting numbers, make sure you know the place values of the numbers. Then write each number underneath the other so that the units (U) figures are in line, all the tens (T) are in line, all the hundreds (H) are in line, and so on. Remember to write the numbers underneath each other.

Example 1

1. Add 1952 and 567.
2. Take away 936 from 7093.
3. Ade has 5673 marbles, Ola has 3426 marbles, and Michael has 887 marbles. How many marbles do they have altogether?
4. Find the total of 90156, 300673 and 65489.
5. The difference between two numbers is 6032. If the larger number is 96005, what is the smaller number?

Solution

1. 1952 + 567 = 2519

2. 7093 − 936 = 6157

3. Ade, Ola and Michael have 9986 marbles altogether.

4. The total of 90156, 300673 and 65489 is 456318.

5. The smaller number is 96005 − 6032 = 89973.

How do you multiply and divide numbers?

Multiply by each digit of the second number in turn, write each result in its correct place, then add the results. For division, work through the number from the left, divide at each step, write down any remainder and bring down the next digit.

Example 2

1. Find the product of 8600 and 150.
2. A big company recently bought 78 new computers, each costing ₦95,000. How much did the company spend?
3. Divide 15648 by 12.
4. 5982 computers are to be shared among 40 schools. How many will each school get, and how many will be left over?

Solution

1. 8600 × 150 = 1,290,000

2. The company spent 78 × ₦95,000 = ₦7,410,000.

3. 15648 ÷ 12 = 1304

1. 12 into 15 goes 1 time. 15 − 12 = 3.
2. Bring down 6 to make 36. 12 into 36 goes 3 times, with remainder 0.
3. Bring down 4. 12 into 4 goes 0 times, with remainder 4.
4. Bring down 8 to make 48. 12 into 48 goes 4 times, with remainder 0.

The quotient is 1304.

4. 5982 ÷ 40 = 149 remainder 22

1. 40 into 59 goes 1 time. 59 − 40 = 19.
2. Bring down 8 to make 198. 40 into 198 goes 4 times (160). 198 − 160 = 38.
3. Bring down 2 to make 382. 40 into 382 goes 9 times (360). 382 − 360 = 22.

Each school will collect 149 computers, and 22 computers will be left over.

Evaluation

1. Find the total of 453323, 642176 and 99510.
2. Take away 301653 from 887321.
3. Find the sum of 666721, 55432, 29255, 387, 554 and 77.
4. Michael collected 1350 oranges from his sister Helen. He gave 546 to Mathew and 123 to Kenny. How many oranges are left in Michael’s hands?

Assignment

1. Multiply the following: (a) 6745 by 356 (b) 89760 by 120.
2. Find the product of 98700 and 4900.
3. Divide the following: (a) 56748 by 24 (b) 640000 by 80.
4. 789 oranges are to be shared equally among 14 brothers. How many will each person get, and how many will remain?