Fractions simplification

The essence of mathematics is its freedom --Cantor G

Ex1.   1.9 x 1.9 - 1.1 x 1.1 = ?
          = (1.9)² - (1.1) ² = 3.61 - 1.21 = 2.40 ( Its simple as you know squares of 19 and 11 )

Ex2.   2.999 x 2.999 - 0.001 x 0.001 = ?
         Here one algebra formula is there to simplify this i.e. a² - b² = (a+b) (a-b)
         Here a = 2.999, b = 0.001
         So 2.999² - 0.001² = (2.999+0.001)(2.999-0.001)
                                        =  (3)(2.998)
                                        = 8.994

Ex3. 5.9x5.9 - 4.1x4.1 = ?   ( try yourself)

Ex4. 56.67 /100 = 5.667/?
        =56.67x100/100x100 = 5.667x1000/1000x?
        =5667/10000 = 5667/1000x?
        =x = 10

Ex5. 1.765/10 = 17.65/?   ( try yourself)