Explanation
If the number of rows and number of columns are to be equal, then the total number of trees will be in the form of x2, which is nothing but a perfect square.
As 1000 is not a perfect square, you need to check for a perfect square above and nearest to 1000.
It's 1024, which is square of 32. So he needs to add 24 more trees to get 1024.
25 is the only perfect square which falls between 20 and 30.
Therefore, option C is correct.
The numbers which will have 1 at their unit place in their squares are the numbers ends with 1 or 9
Because 1×1 = 1 and 9×9=81
Here, 225=3×3×5×5=(3×5)2=(15)2
Therefore, option C is the correct answer.
In (64)2, the digit in unit's place is the last digit at the multiplication of
4×4=16_
So, 6 at units place
Therefore, B is the correct answer.
Since, the last digit of number 427 is 7, 7 being an odd number the whole square number will be odd because 7×7=49
Thus, square root of an odd number is odd
Therefore, option B is the correct answer.
We know
112=121 comes before 140
122=144 lies between 140 & 150
132=169 lies after 150
Only144 lies between 140 & 150
So 144 is the only perfect square number between 140 & 150
Only 81 is a perfect square number between 80 & 90.
92=81,
102=100, before its 82=64 .
(64,81,100) only 81 lies between 80 & 90.
Step -1: Find prime factors of 625.
Prime factors of 625=5×5×5×5.
Step -2: Find the square root of 625.
√625=√5×5×5×5
=5×5
=25
Hence, B is the correct option.
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