SQUARING
Note-:
            We must consider the importance of squaring because many problems we solve easily if we learn squaring . some basic methods of squaring is given below

 (A) . Square of the number whose last digit is 1 or ending with 1 -:

To get the square of any such number , we write the square of previous number and then add the previous number and the number whose square being asked .

Let an example -: The square of 61

61^2 (61×61) -: 60^2 + 1(60+61) = 3600 + 121 = 3721
 Similarly, 91^2 = (90^2) +1(90+91) = 8100 + 181 = 8281
and  41^2(41×41) = (40^2) +1(40+41) = 1600 + 81 = 1681

And   161^2 = (160^2) + (160+161) = 25600+ 321 = 25921

And.    1111^2 = (1110^2) + 1(1110 + 1111) = 1232100+2221 = 1234321.

NOTE-:  by using sign "^" we write power of any number like 61^3 means cube of 61 or (61×61×61) ,118^5 means 118 to the power 5  or (118×118×118×118×118).

NOTE -: We see above that 1 is multiply by addition  {1(1110+1111)} here 1 is the difference between the number whose square is required and the previous number . {1111 -1110=1}

(B). Square of the numbers whose last digit is 2 or 8 -:
Let an example
(a) 18^2  = (20^2) - 2(18+20) = 324

 (b) 112^ 2 = (110^ 2) + 2(110+112)  = 12100 + 444 = 12544

 (C) 38^ 2 = (40^2) - 2(38+40)  = 1600 - 156 = 1444 .

 Note -: here we see that 2 is multiply which is difference difference between the number whose square is required and the previous or next number .like
112 - 110 = 2
40 - 2 = 38

(C) . square of the number whose unit digit is 3 or 7 -:

Let an example -:
(a). 63^2 = (60^2) + 3(63+60) = 3600 + 369 = 3969 .

(b). 137^ 2 = (140^2) - 3(137+140) = 19600 - 831 = 18769

(C). 47^2 = (50^2) - 3(50+47) = 2500 - 291 = 2209

(d) . 2347^ 2 = (2350^2) - 3(2347+2350) = 5522500 - 4691 = 5517809 .


(D) . square of the numbers whose unit digit is 4 or 6 -:

(a) 46^2 = (50^2) - 4(50+46) = 2500 - 384 = 2116 .

(b) . 46^2 = (40^2) + 6(40+46) = 1600 + 516 = 2116.

(C). 54^2 = (50^2) + 4(50+54) = 2500 + 416 = 2916 .

(d) . 124^2 = (120^2) + 4(120+124) = 14400+ 976  =15376.

NOTE -: Generalized formula for this method is given below
Let ," N"is the number whose square is to be calculated and "B" is the base and "d" is the difference between "N"and "B" then
 (1) . N^2 = (B^2) + d(B + N)        , when B<N .
(2) . N^2 = (B^2) - d(B + N)          , when B>N .

(E) Square of the number whose unit digit is 5 -:

Note -: any number whose unit digit is 5 . we write the 25 in rightmost in place of 5 , then we multiply the rest number with its successive number ( i.e one more than the previous one ). Look at some examples

Example -: square of 45
Solution -: 45^2 =  step 1. 25
                                 Step 2. 4(4+1) = 20
                                 Step 3. 2025
So , (45^2) = 2025 Answer.
 (2). 125^2 = step 1. 25
                       Step 2. 12(12+1) = 156
                       Step 3. 15625
So , (125^2) = 15625 answer.
(3). 345^2 = step1. 25
                      Step2. 34(34+1) = 1190
                       Step 3. 119025
So, (345^2) = 119025 .

Note -:
(a) . the number whose unit digit is 0,1,5 and 6 always give the same unit digits respectively ,on squaring.
(b). 2,3,7and 8 never appear as unit digit in the square of a number.
(C). PERFECT SQUARE -: The square of any natural number is known as perfect square e.g.,4,9,16,25,81,121,625,3600,2401,256,196,    324,225,289,361,400,441, etc.