double * double = imprecise result

[rnrn]

I have a java class that multiplies one double with another. The result is sometimes imprecise, for example
7.2 * 21 gives 151.20000000002 when it should be 151.2
and
1.2 * 9 gives 10.799999999 when it should be 10.8.

Can anyone tell me why this is so and what datatype I should use to ensure precision in arithmetic?

 

[jfryer]

Have a look in the java API documentation at

BigDecimal

for
"Immutable, arbitrary-precision signed decimal numbers. A BigDecimal consists of an arbitrary precision integer unscaled value
and a non-negative 32-bit integer scale, which represents the number of digits to the right of the decimal point. The number
represented by the BigDecimal is (unscaledValue/10scale). BigDecimal provides operations for basic arithmetic, scale
manipulation, comparison, hashing, and format conversion"

This may help. -------------------------------------------
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