Multiplying Decimals

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I am trying to translate a decimal to time. For example, 7.5 to 7:30. Below
is my code. If I can multiply the .5 by 60, I will get the :30, but I can't
figure out how to tell the program to multiply only the .5 and not the entire
number (TimA or 7.5).

TextBox7.Text = CStr(Int(TimA)) & ":" & Format((TimA * 60), "00")

Any help would be greatly appreciated. Thanks!
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