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SQUARES AND SQUARE ROOTS 91

Write five numbers which you can decide by looking at their one’s digit that they
are not square numbers.
2. Write five numbers which you cannot decide just by looking at their unit’s digit
(or one’s place) whether they are square numbers or not.

• Study the following table of some numbers and their squares and observe the one’s
place in both.
Table 1

Number Square Number Square Number Square

1 1 11 14 21 441
2 4 12 144 22 484
3 9 13 169 23 529
4 16 14 196 24 576
5 25 15 225 25 625
6 36 16 256 30 900
7 49 17 289 35 1225
8 64 18 324 40 1600
9 81 19 361 45 2025
10 100 20 400 50 2500

The following square numbers end with digit 1.

Square Number TRY THESE

2
2
2
1 1 Which of 123 , 77 , 82 ,
2
2
81 9 161 , 109 would end with
digit 1?
121 11
361 19
441 21
Write the next two square numbers which end in 1 and their corresponding numbers.
You will see that if a number has 1 or 9 in the unit’s place, then it’s square ends in 1.

• Let us consider square numbers ending in 6.

Square Number TRY THESE

16 4 Which of the following numbers would have digit
36 6 6 at unit place.

196 14 (i) 19 2 (ii) 24 2 (iii) 26 2
256 16 (iv) 36 2 (v) 34 2