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Question

38^2-37^2

Is there any additional method, if there can you please show

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Solution

I can tell you the general method.
38×38-37×37
=>1444-1369
=>75
Answer is 75.

There are some short cut methods. But it may be applicable for a short range or not good when number is large(depending upon the method used).
So i recommend you to do general method.

However, i will tell you a shortcut method for finding square.(Remember there are lots of short cut methods and this is only one of them)

Method:
This method uses the identity (a + b) 2 = a 2 + 2ab + b 2
Step 1 : Find 572
Here a = 5 and b =7
Column I Column II Column III
a2 2 x a x b b2
52= 25 2 x 5 x 7 =70 72= 49

Step II: Underline the digit of b 2 ( in column III) and add its tens digit, if any, to 2 x a x b (in column III)
Column I Column II Column III
a2 2 x a x b b2
25 70 + 4 = 74 49

Step III: Underline the digit in column II and add the number formed by tens and other digit, if any, to a2 in column I.
Column I Column II Column III
a2 2 x a x b b2
25 + 7 70 + 4 = 74 49

Step IV: under the number in column I
Column I Column II Column III
a2 2 x a x b b2
32 74 49

Write the underlined digits from the unit digit.
Therefore, 57 2 = 3,249 .

Hope it helps!


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