flixblixclix wrote:we can find the sqare root by two methods
1)prime factorisation
2)Division method
PRIME FACTORISATION
Q)Find the square of 9801...
Sorry, I rather prefer the easier method of:
1) Determining the first two digits
2) Determining the last digit
With the condition: THE GIVEN NUMBER IS A PERFECT SQUARE
OK, let's assume 9801 is a perk (perfect square number)
1) the first digit is 98
2) the last digit is 1
There is a technique w/c I called "Ten-Square Complements" in which there are always a pair of single digit numbers, when added will give us a sum of 10 and which their 'index squares' end, with the same digit number, such:
1 + 9 = 10, square of 1 = 0
1 while square of 9 = 8
1
2 + 8 = 10, square of 2 = 0
4 while square of 8 = 6
4
3 + 7 = 10, square of 3 = 0
9 while square of 7 = 4
9
4 + 6 = 10, square of 4 = 1
6 while square of 6 = 3
6
(Except 0 and 5, which don't have a pair)
9801 is a 4 digit number,
1) Regroup by twos - 98'01
2) Consider the first two digit, 98
The nearest square but less than 98 is 81 and its equivalent square root value is 9
3) The last digit of 98'0
1 is, of course, 1
There is a pair of single digit numbers with squares ending in 1 and these are 1 and 9
4) So,we have two possible square roots 91 and 98 and only one of them is correct
To determine which of the two is the right answer, simply consider the first digit of the possible answers (91 or 98) and "add 1" (that is, 9 + 1 = 10) and multiply to the original digit (9)
9 x 10 = 90
Conditions:
1) If the product (90) is less than the first two digits of the given problem (98), consider the much higher value among the two possible answers (between 91 and 98, choose 98)
2) If the product (90) is greater than the first two digits of the given problem (98),(which is not true or contradicting, in this case), consider the much lower value among the two possible answers (between 91 and 98, choose 91)
In this case, 90 is less than 98, therefore, (with the assumption that 9801 is a perk), the right answer would be: 98
NOTE: To make condition 2 agreeable, the given problem must be = 8,281
...2) If the product (90) is greater than the first two digits of the given problem (82), consider the much lower value among the two possible answers (between 91 and 98, choose 91)
Both prime factorization and division method were both traditionals and we're familiar with them.
These "alternative methods", go beyond the traditionals, or simply stated as "breaking the conventional strict rules we learned in the class rooms"