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 a
2 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!