`a) 578 + 125 + 422 + 375`

` = (578 + 422) + (125 + 375)`

` = 1000 + 500 = 1500`

`b) 36.11.25.9`

` = 4.9.11.25.9`

` = (4.25) . (11.9).9`

` = 100 . 99 . 9 = 9900 . 9`

` = 89100`

`c) 27.16 + 81.21 + 9.21.3`

` = 27.16 + 27.3.21 + 27.21`

` = 27.16 + 27.63 + 27.21`

` = 27.(16 + 63 + 21) = 27 . 100 = 2700`

`d) 36.13 + 64.37 + 9.4.87 + 64.9.7`

` = 36.13 + 64.37 + 36.87 + 64.63`

` = 36.(13 + 87) + 64.(37+63)`

` = 36. 100 + 64.100`

`= 100 . (36+64) = 100. 100 = 10000`

`e) 2.14.98 + 7.4.32 - 28.30`

`= 28.98 + 28.32 - 28.30`

` = 28.(98+32-30) = 28. 100 = 2800`

`f) 2^2 . 85 + 15.2^2-2020`

` = 4 . 85 + 4.15 - 2020`

` = 4. (85 + 15) - 2020`

` = 4. 100 - 2020 = 400 - 2020 = -1620`

`g) (56.35 + 56.18) :53`

` = 56 . (35+18) : 53`

` = 56 . 53: 53`

` = 56`

`h) (158.129 - 158.39) : 180`

` = 79. 2. (129 - 39) : 180`

` = 79 . 2 . 90: 180`

` = 79.180 : 180 = 79`

`i) 123.456 + 456.321 - 256.444`

` = 456.(123 + 321) - 256.444`

` = 456. 444 - 256.444`

` = 444. (456 - 256)`

`= 444. 200 = 88800`

`j) (252 + 2.28 - 5.28) : 28`

` = (28. 9 + 28. 2 - 28.5):28`

` = 28 . (9+2-5) : 28`

` = 6`