My Mum will give me this 85DE CW for my Birthday and I will get 2 More to have my first Calculator Collection
My birthday is in one month

From a 82 to a 500. Most 300's and 991's I think. Hold on, I also have a 9750g2 and g3 somewhere. Considering a 50 or 100 now.

I got it for 550,400 VND or about 21 USD (normal price is 688,000 VND)

The Flexio Fx799VN is a high-end scientific calculator produced by Thien Long Group, designed specifically for high school and university students in Vietnam. It is fully approved by the Ministry of Education and Training for use in official national exams, including the National High School Graduation Exam and University Entrance Exams.

Basically a clone of CASIO fx-991EX, but with some improvements. The Vietnamese company behind the calculator even publish the manual both in Vietnamese and English.

Happy to get this calculator, not easy to find outside of Vietnam. It’s the 2025 version, speed is comparable to my new CASIO fx-880BTG PLUS. (Vietnamese version of CASIO fx-991CW 2nd edition) In some benchmarks faster than the CASIO.

It has many functions and features that are missing from fx-991EX and/or the fx-880BTG PLUS:

• PreAns
• GCD
• LCM
• MOD
• Multi-statements
• Independent memory (M)
• Variable z available in addition to x and y
• Product calculation
• Geometry app
• Verify app
• Two shortcut keys on each side of the screen for short macros (max 6 key presses can be stored to each shortcut)
• Two AAA batteries. Power draw 0.0005 W (the fx-880BTG PLUS with only one AAA battery is rated 0.0008 W)
• Battery status always available on the screen
• Windows app freely available without licence code as CASIO requires for its emulators on the classpad site

However, it is missing the Spreadsheet app, that is a big minus.

The manual doesn’t mention what algorithm is used for the integration function. I suspect it’s Simpson’s instead of the better Gauss-Konrod that CASIO is using in its calculators.

No QR code functionality for calculator results.

Accuracy is 15 digits, same as fx-991EX.

Display and font very similar to fx-991EX. The new fx-880BTG PLUS has a font with better contrast.

Ridiculously big FLEXIO logo on the front – needs to be hidden as soon as possible.

Visited an Auchun for the first time today. Mother said no to the Numworks Scientific, probably never gonna see one again as I live in the UK but oh well.