Case 1: Below a base number.
Base number can be 10, 100, 1000 or higher.
997^2 = ?
1000 - 997 = 3
997^2 = 997 - 3 | 3^2
997^2 = 994 | 009 ••
997^2 = 994009
•• Number of zeros of base number indicates number of digits for the last group of the answer. That is why 3^2 = 009 .
Other examples:
96^2 = ?
100 - 96 = 4
96^2 = 96 - 4 | 4^2
96^2 = 92 | 16
96^2 = 9216
9987^2 = ?
10000 - 9987 = 13
9987^2 = 9987 - 13 | 13^2
9987^2 = 9974 | 0169 ••
9987^2 = 99740169
Case 2: Above the base number.
13^2 = ?
13 - 10 = 3
13^2 = 13 + 3 | 3^2 •••
13^2 = 16 | 9
13^2 = 169
••• If a number is below the base, subtract. If a number is above the base, add. That is why 13 + 3 and not 13 - 3.
Other examples:
108^2 = ?
108 - 100 = 8
108^2 = 108 + 8 | 8^2
108^2 = 116 | 64
108^2 = 11664
1012^2 = ?
1012 - 1000 = 12
1012^2 = 1012 + 12 | 12^2
1012^2 = 1024 | 144
1012^2 = 1024144
Case 3: Near a multiple of base number.
204^2 = ?
Base number is 2*100. Follow the same procedure with case 1 and case 2, but this time, first group of the answer will be multiplied by base factor (2).
204^2 = ?
204 - 200 = 4
204^2 = 2*(204+4) | 4^2
204^2 = 416 | 16
204^2 = 41616
Other examples:
196^2 = ?
200 - 196 = 4
196^2 = 2*(196 - 4) | 4^2
196^2 = 2*192 | 16
196^2 = 384 | 16
196^2 = 38416
6080^2 = ?
6080 - 6000 = 80
6080^2 = 6*(6080+80) | 80^2
6080^2 = 6*6160 | 6400
6080^2 = 36960 + 6 | 400 ••••
6080^2 = 36966400
•••• Number of zeros of base number indicates number of digits for the last group of the answer. Carry over the excess digits to the first group ( 36960+6).
#Matamata
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