√200 is irrational — 14.1421 to four decimal places, 14.14 to two
√200 ≈ 14.1421. 200 is not a perfect square, so the root is an irrational number and 14.1421 is a rounded value. Below is where that answer comes from, how to check it in one step, and how to estimate any square root without a calculator.
√200 ≈ 14.1421. Rounded to two decimal places that is 14.14.
200 is not a perfect square, so its root is not a whole number. The nearest whole numbers either side are 14 and 15: 14 × 14 = 196 and 15 × 15 = 225, and 200 sits between those two, so √200 sits between 14 and 15.
The root is irrational, which means the decimal never terminates and never settles into a repeating block. 14.1421 is a rounded value, not the exact one — the exact answer can only be written as √200 itself, or in simplified form as 10√2.
Square your answer and see how close it lands. 14.14 × 14.14 = 199.9396, which is within a whisker of 200 — close enough to confirm the root without a calculator agreeing digit for digit.
Because rounding happens at the end, squaring a rounded root will never give back exactly 200. That gap is the rounding, not an error in the root.
√200 simplifies to 10√2, because 200 = 100 × 2 and 100 is a perfect square. Pulling the 10 out from under the root sign is the standard way to write it in exact form.
Check it numerically: 10 × √2 = 10 × 1.4142 = 14.1421, the same value as √200. Simplified form is the same number written more tidily, not a different one.
Find the two square numbers it falls between and you have already bracketed the answer. 196 and 225 are 14² and 15², and 200 lies between them, so the root is between 14 and 15.
To sharpen the estimate, see how far along the gap the number sits. From 196 to 225 is a jump of 29, and 200 is 4 of the way in, so the root lands roughly 14.14. That linear guess is usually right to within a tenth, which is plenty for a sanity check.
Knowing the square numbers up to 25² by heart is what makes this instant. They are 1, 4, 9, 16, 25, 36, 49, 64, 81, 100, 121, 144, 169, 196, 225, 256, 289, 324, 361, 400, 441, 484, 529, 576 and 625.
Square roots turn up any time an area, a distance or a spread has to be turned back into a length. The diagonal of a rectangle, the standard deviation of a set of numbers, the distance between two points on a grid — all of them finish with a square root.
That is why estimating one quickly is worth more than memorising a decimal. Being able to say "√200 is a bit over 14" in a second is what keeps a longer calculation moving.
The square root of 200 is approximately 14.1421, or 14.14 to two decimal places. It is an irrational number, so the decimal does not end.
No. 200 falls between 196 (14²) and 225 (15²), so its square root is not a whole number.
14 × 14 = 196. Squaring is the inverse of taking a square root, so it is also the way to check a root you have just worked out.
Bracket it between the two nearest square numbers — 196 and 225 — then judge how far along the gap 200 sits. That gets you to roughly 14.14, which is close enough for almost any mental check.
√200 = 10√2, because 200 = 100 × 2 and 100 is a perfect square.
The square numbers up to 25² each have a page here, and the square numbers index lists them all in order.