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(*) Squaring A Number In The Range
(90 – 99):
A.
This method comes from algebra:
(100 – a)2
= 100((100 – a) – a) + a2
B.
Using numbers instead of variables we get the following:
1.
Find the difference between the number and 100.
2.
Square the result of step 1 and write it down (make sure it takes up 2
place values).
3.
Subtract the result of step 1 from the original number and write it down.
Ex [1] 972 =_________.
a)
100 – 97 = 3.
b)
32 = 9. Write 09
to take up 2 place values.
c)
97 – 3 = 94. Write 94.
d)
The answer is 9409.
Ex [2] 922 =_________.
a)
100 – 92 = 8.
b)
82 = 64. Write
64.
c)
92 – 8 = 84. Write 84.
d)
The answer is 8464.
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