Question

Find the Square Root of 6561 by finding it's ones and tens digits.​

Answer 1

$\large\underline{ \underline{ \sf \maltese{ \: Question:- }}}$

• Find the Square Root of 6561 by finding it's ones and tens digits.

$\large\underline{ \underline{ \sf \maltese{ \: Method \: to \: use:- }}}$

• Tens and Ones Method

$\large\underline{ \underline{ \sf \maltese{ \: </strong><strong>Explanation</strong><strong>:- }}}$

The ones digit of the given number is 1.

So, the ones digit of the square root is either 1 or 9. Let us strike out two digits from the right and now we get the number 65. The square of 8, i.e 64, is the largest square that is less then 65. 8^2 = 64 < 65 , whereas 9^2 = 81 > 65.

Hence, the tens digit of the square is 8.

So, the square root of 6561 is either 81 or 89.

But, (89)^2 = 7921 , Which is not equal to 6561...

Hence , √ 6561 = 81

More For Knowledge:-

$\underbrace\red{\boxed{ \sf \blue{ Rules \: of\: Tens \: and \: Ones \: Method }}}$

The square root of perfect squares up to four digits can be easily found by finding their ones and tens digits. To find out the square root of a given number, we have to follow these steps:

• Step 1: Observe the ones digit of the perfect square and determine the digit in the ones place in the square root, as discussed earlier. If the perfect square has l or 4 or 6 or 9, then there are two possible ones digits.
• Step 2: Strike out the last two digits from the right of the number. If nothing is left, we stop. The digit obtained in step l is the answer.
• Step 3: Now consider the leftover number, and determine the largest 1-digit number whose square is less than or equal to this leftover number. This is the tens digit of the square root.

Note:

If there are two possible answers, then the correct answer can be found by the actual multiplication method.

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