This presentation was created by me for the Scholars for Change Campaign, IIM Ahmedabad for the underprivileged children. Scholars for Change is a campaign of Education Innovation Bank at IIM Ahmedabad. This campaign seeks to give to underprivileged children access to high quality, interesting content in Science and Math, so that they can learn on their own, in their own language, with fun and play.

1. Properties of Square
Numbers
By Parth Nagpal

2. What is a Square Number?
• A number when multiplied with itself gives a square number.
For Example,
2 × 2 = 4
3 × 3 = 9

3. Look at this table
Number Square Number Square
1 1 11 121
2 4 12 144
3 9 13 169
4 16 14 196
5 25 15 225
6 36 16 256
7 49 17 289
8 64 18 324
9 81 19 361
10 100 20 400

4. Some Properties of Square Numbers
• The unit digit of a number ending in 0 is always 0.
• The unit digit of a number ending in 1 or 9 is always 1.
• The unit digit of a number ending in 2 or 8 is always 4.
• The unit digit of a number ending in 5 is always 5.
• The unit digit of a number ending in 4 or 6 is always 6.
• The unit digit of a number ending in 3 or 7 is always 9.
So, the unit digit of a square number is always 0,1,4,5,6,9.

5. Examples
Number Square
10 100
20 400
Number Square
9 81
11 121
Number Square
12 144
18 324
Number Square
14 196
16 256
Number Square
5 25
15 225
Number Square
13 169
17 289

6. Practice Questions
Q1. Square of which of the following numbers will have 1 in its unit place?
29, 25, 18, 31, 49, 52, 21, 55
Q2. Square of which of the following numbers will have 6 in its unit place?
24, 85, 13, 76, 54, 41, 58, 66
Q3. Square of which of the following numbers will have 9 in its unit place?
36, 23, 77, 84, 47, 53, 67, 22