Question

I am doing a calculation of values using Microsoft Excel vba.

I have a portion of codes like the below:

INT(151.2 * 100)
I notice that the result from this calculation is 15119 but the correct result should be 15220.

It is ok if i remove the INT()
151.2 * 100
The result returned will be 15220.

Can anyone advise why is there such a difference and whether it is correct to simply remove the INT() to achieve the correct result?

Answer 1

Floating-point arithmetic.

a = (151.2 * 100)
Print Int(a)
15119
Print a
15120
Print a = 15120
False

There is no double-precision number to represent the result of 151.2 * 100 exactly as 15120. The closest one is apparently just under 15120. When you Int it, it gets truncated, i.e. rounded down to 15119.

Instead of truncating, you could round:

Print CInt(a)
15120
Print Round(a)
15120

Note that if you have a variable i of type Integer and you just say i = 151.2 * 100 as you suggest, then you are implicitly coercing the result to an integer i.e. implicitly saying i = CInt(151.2 * 100). I think it’s better practice to be explicit.