When I put the equal sign in two of these symbols ~, it means that it is to correct and round. When 0.428.. is rounded to 2 decimal places, the 2 in the hundreths place will round up as 8 behind it is more than 5. *If the number behind it example 0.423, is less than 5, it will remain the same and become 0.42 (2.d.p) :)