No, a square root doesn't have to be a whole number. The square root of 2.25 is 1.5. It could be said that most square roots are not whole numbers. Take just the first few integers (counting numbers). Find the square roots of the numbers 1 through 10 and you'll find three of the numbers have whole number square roots (1, 4 and 9). The other seven don't. For the numbers 11 through 20, there is only 1 number with a whole number square root (16).
perfect squares
They are the perfect squares.
Square roots of negative numbers are imaginary.
The square root of a positive whole number, N, is a number which, when multiplied by itself equals N. If N = 0 then the square root is also 0. If N is greater than 0 there will be two such numbers: one positive and the other its negative equivalent. If N is a perfect square the square roots will, themselves, be whole numbers. Otherwise, they will be irrational numbers. If N is a whole number less than 0 then there are no real square roots. Although there are square roots in the complex field, the fact that you ask this question is indicative that you are not yet ready to tackle complex numbers.
Every whole number
No, a square root doesn't have to be a whole number. The square root of 2.25 is 1.5. It could be said that most square roots are not whole numbers. Take just the first few integers (counting numbers). Find the square roots of the numbers 1 through 10 and you'll find three of the numbers have whole number square roots (1, 4 and 9). The other seven don't. For the numbers 11 through 20, there is only 1 number with a whole number square root (16).
Numbers with square roots that are whole numbers
perfect squares
They are the perfect squares.
Square roots of negative numbers are imaginary.
Rational numbers whose square roots are whole numbers are themselves whole numbers. They are called square numbers, e.g. 1, 4, 9, 16, 25 and so on.
The square root of a positive whole number, N, is a number which, when multiplied by itself equals N. If N = 0 then the square root is also 0. If N is greater than 0 there will be two such numbers: one positive and the other its negative equivalent. If N is a perfect square the square roots will, themselves, be whole numbers. Otherwise, they will be irrational numbers. If N is a whole number less than 0 then there are no real square roots. Although there are square roots in the complex field, the fact that you ask this question is indicative that you are not yet ready to tackle complex numbers.
Very rarely. Square roots are only whole numbers for perfect squares.
There are no two whole numbers between -0.7 and +0.7.
Some square roots of whole numbers are integers, some of them are irrational numbers. The square root of four for instance is a rational number, 2. The square root of two however is an irrational number, approximately 1.414211356.
Every integer is a rational number, and some integers are perfect squares. These are the only rational numbers to have an integral square root.