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To square a number is to multiply it by
itself. The square root of a number x is a number y such that y2
= x. The square root is the inverse* operation of
the square. |
For example: 142 = 196. The square root of 196 is
14. The
square of 14 is the square of the square root of 196, which is 196, of
course. Likewise the square root of the square of 14, 196, is 14 |
| Note
here that the square of a
negative number is always
positive. This means that any positive number has TWO
square roots - a positive one and the negative of that same number.
This also means that negative numbers do NOT have normal square roots.
Look up imaginary and complex numbers. |
The square of 5 is 25. The
square of -5 is also 25. The square root of 25 is either 5 OR -5. For this tutorial, we will just do positive roots. |
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Step 1: Pair off all the digits in the number, both ways from the decimal point. If you have to add zeroes on the right to make a pair, do so, just so all digits to the right of the decimal are in pairs. You don't have to have the first digit paired if it is to the left of the decimal point. |
For example: 521.4 should be paired off as 5 21.40
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Step 2: Set up the frame and copy the decimal to the top |
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Step 3: Find the largest whole number whose square is less than the first digit or digit pair. Put this on top. |
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Step 4: Square it and subtract it from the first digit or digit pair. |
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Step 5: Bring down the next 2 digits |
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| Step 6: Multiply your entire "dividend" (the
number on top) so far by 2, and place to the left of the new set of
digits. |
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Step 7: GUESS how many times this "divisor" will go into the new number (ignore the last digit). If it is close to exact, pick the next number down. Put this guess on top AND IN THE SINGLE BLANK SPACE YOU LEFT. |
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Step 8: Multiply your guess times the "divisor" and subtract from the new number. If the product was too big, reduce the guess by 1 and try again. If the remainder is bigger than the divisor, you can increase the guess by 1, but remember that the guess is also in the divisor. If the remainder equals the divisor, do not increase the guess. |
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Step 9: go back to step 5 and repeat until you use up all the pairs. The number on top is the square root to as many places as you tried. |
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