SQUARING A NUMBER IN THE RANGE OF 40-49

Squaring A Number In The Range (40 – 49):

   A.  This method comes from algebra:

                        (50 – a)2 = 100(25 – a) + a2

   B.  Using numbers instead of variables we get the following:

1.  Find the difference between the number and 50.

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 25.  Write this result.

Ex [1]  492 =_________.

a)      The difference from 50 is 1.

b)      12 = 1.  Write 01 to take up 2 place values.

c)      25 – 1 = 24.  Write 24.

d)      The answer is 2401.

Ex [2]  422 =_________.

a)      The difference from 50 is 8.

b)      82 = 64.  Write 64.

c)      25 – 8 = 17.  Write 17.

d)  The answer is 1764.