Final answer:
To approximate the square root of 18, identify the nearest perfect squares (16 and 25) and determine that it lies between 4 and 5. Using estimation or a calculator, the square root of 18 is about 4.2, which can then be plotted on a number line between 4 and 5 closer to 4.
Step-by-step explanation:
To approximate the square root of 18 to the nearest tenth, first identify the perfect squares closest to 18, which are 16 (42) and 25 (52). The square root of 18 is between 4 and 5. Since 18 is closer to 16 than to 25, its square root will be closer to 4. By using a calculator, or estimating, we find that the square root of 18 is approximately 4.2. To plot the number on a number line, draw a line and mark points at regular intervals, indicating the integers. Place a point between 4 and 5 that is closer to 4 to represent sqrt(18) ≈ 4.2.
A square root is the inverse of squaring. What is an inverse? Inverses are opposites, so for example, the inverse of adding is subtracting. The inverse of multiplying is dividing. These are opposites of each other, and have an inverse relationship.
When you take the square root of a number, you may get a decimal number. If you're able to get a whole number as an answer, then the original number you were finding the square root of is a perfect square number. Examples of a list of perfect squares include the numbers 4, 9, 16, 25, 36 and 49.