This accepted answer does not help if I need to do math with the resulting value. Try this: 5.02 * .06 where 5.02 is the cost of the product and .06 is the sales tax rate. Once you move the NSNumber to a Double or Float the cost value becomes 5.0199999... and don't trust Playground examples. They show the .round and *100 /100 tricks working but in compiled Swift they don't! I am going through a nightmare of code to write a reliable rounding a Double to 2 decimal positions so I can do a calculation!

Most of these responses are referring to Version numbering and not Build Numbers. VV.RR.PP VV = Version, RR = Release with version, PP = Patch or Fix within release. Build numbers are often used to track builds of software independent of release, and it is important that Apple and other software distributors not INTERFERE with these numbering schemes, as many organizations track all platforms of revisions. These build numbers are also connected to Certifications. For example an FDA Validation may be connected to a particular build number. Also EMV certifications are connected to build numbers.