Second Term Lesson Note for Week Five
Class : Primary Four
Subject : Mathematics
Topic : Squares and Square root of Numbers.
Duration : 80 Minutes
Period : Double Period
Reference Book :
New Method Mathematics for Primary Schools, Book 4, by Learn Africa.
Lagos State Unified schemes of work for Upper Primary School, Primary 4 – 6.
Online Resources
Instructional Material : Chart showing the squares of numbers
Learning Objectives : By the end of the lesson learners will be able to
i. discover what squares and square roots mean
ii. solve problems involving the calculation of squares of numbers.
iii. Solve problems involving square root of Numbers.
SQUARES AND SQUARE ROOTS OF NUMBERS ( 1- digit and 2 – digit numbers)
Example: 1:
find 2² + 4²
=( 2 x 2) + ( 4 x 4)
= 4 + 16
= 20
Example 2: find 4² – 2²
= (4 x 4) – (2 x 2)
= 16 – 4
= 12
Example 3: find 3² + 3²
= (3 x 3) + (3 x 3)
= 9 + 9
= 18
Example 4: 10² – 4²
= (10 x 10) – (4 x 4)
= 100 – 16
= 84
Exercise 1
Find the value of:
1. 4² + 6²
2. 5² – 2²
3. 5² + 7²
4. 10² – 5²
5. 8² + 10²
6. 8² – 6²
7. 2² x 5²
8. 3² x 4²
9. 6² x 2²
9. 2² x 3² x 5²
10. 3² x 4² x 5²
SQUARE OF 2-DIGIT NUMBER
The squares of two-digit numbers are (in short form) 10², 11², 12², 13², … 99².
To calculate the squares of two digit numbers we may use any of these methods.
a) Multiply the number by itself, i.e. using multiplication method.
b) Find the square from the square table.
c) Count the dots from the square pattern.
This method may be too cumbersome at a later stage
Examples
Study the workings to find 14².
Solution: (Multiplication method)
14² = 14 × 14
(10+4)× (10+4)
10(10+4) + 4(10+4)
100+40+40+16
=196
Exercise
Solve each of the following:
1. 42² 2. 9²
3. 10² 4. 12²
5. 11² 6. 15²
7. 17² 8. 16²
9. 18² 10. 20²
Tables of squares and square root of Numbers.
| Numbers | Squares | Perfect square |
| 11 | 11 x 11 | 121 |
| 12 | 12 x 12 | 144 |
| 13 | 13 x 13 | 169 |
| 14 | 14 x 14 | 196 |
| 15 | 15 x 15 | 225 |
| 16 | 16 x 16 | 256 |
| 17 | 17 x 17 | 289 |
| 18 | 18 x 18 | 324 |
| 19 | 19 x 19 | 361 |
| 20 | 20 x 20 | 400 |
| 30 | 30 x 30 | 900 |
| 40 | 40 x 40 | 1600 |
| 50 | 50 x 50 | 2500 |
| 60 | 60 x 60 | 3600 |
1. √625 = 25
2. √(2500 x 400) = 1000
Evaluation :
Find the values of the square roots of :
1. 6 1/4 =
2. 169 – 49 =
3. 1600 – 900
4. What is the value of √3600 + 9²
Conclusion : At the end of the lesson learners were able to answer the questions correctly.