HP 39&40 series

HP 39g+
Predecessor	HP 39g
Successor	HP 39gs
Programming
Other

HP 40g
Predecessor	HP 38G
Successor	HP 40gs
Programming
Other

HP 39g
Predecessor	HP 38G
Successor	HP 39g+
Programming
Other

The HP 39g, HP 40g, HP 39g+, HP 39gs, HP 40gs, and HP 39gII are algebraic graphing calculators from HP produced between 2000 and 2013.

HP 39g

HP 40g

HP 39g+

HP 39gs

HP 39gs
Calculator

Predecessor	HP 39g+
Successor	HP 39gII
Display type	LCD
Display size	131x64px
Programming
Other

The HP 39gs is by far the most common calculator in the 39/40 series. They can often be found in new or lightly used condition for around 20USD.

HP 40gs

HP 40gs
Programming

Predecessor	HP 40g
Successor	HP Prime G1
Other

The HP 40gs was released in 2006 as a CAS-enabled counterpart to the HP 39gs in European markets. The CAS used is based on Erable, the same CAS used in the 48 series, as well as the 49/50 series. In order to accommodate the CAS software, the 40gs has an expanded 2MB memory compared to the 39gs' 1MB. Other than this difference, the hardware specs between the 39gs and the 40gs are identical. 256kB of RAM, and a 75 MHz ARM9 processor.

The calculator's HOME interface is almost identical to the other calculators in the series, even the 38g. The only difference is the "CAS" menu that is accessible by pressing the rightmost function key, and the CAS interface is very similar to that of the 49/50 series' equation writer.

Unlike many of HP's other calculators, the 40gs has a strictly infix input notation, and does not feature a RPN mode.

HP 39gII

The HP 39gII was a major departure from the rest of the series in terms of design, with it much more closely resembling the HP 10s and the later HP Prime.

HP 39gII
Programming
Predecessor	HP 39gs
Successor	HP Prime G1
Other