146 is fine. Yo do not need a decimal point nor trailing 0s.
146 is an integer and so cannot be expressed as a decimal fraction.
The number IS in decimal notation!
3.88 is decimal notation.
decimal notation of 3.159 = 3.159
42.4 as decimal notation = 42.4
decimal notation of 335 = 335.0
0.05 is already in decimal notation.
It is already in decimal notation as 4.8
300 is already in decimal notation.
decimal notation of 960000 = 900000 + 60000
537 in decimal notation = 537.0
1.46