My Unisonic LC1416 Calculator displays 1000 as 000

It is so old there is no data, just people selling old ones. There is an advert for the battery cover and by the looks of it, it takes 4 x AA or AAA batteries. In the light it is solar powered, in dim light, the batteries. There is nothing fancy about the batteries.

https://www.google.com/search?q=unisonic+lc1416+calculator+replacement+battery

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No. you can't but stock af anything at FIXYA. This is strictly a Q/A forum where members like you and me help each other answering questionss or giving answers to fix problems.

Somehow I feel that you Unisonic Calculator is quite a vintage piece and no parts of it are for sale anywhere.
OK, wait some time, maybe someone can give you a better tip.

Time to buy a new calculator

http://elitepdf.com/page/unisonic-calculator-xl-1267.html

The calculator is dead. It's time to replace it.

There are two separate issues here.

Your calculator is in Algebraic mode. To switch to RPN, press MODE 5 .

Your calculator is also in Octal mode. To switch to Decimal, press right-shift 1 1 .

If the ribbon is fabric, you have to get a replacement. As for paper check several suppliers if you want to buy quantity otherwise a roll will do.

I think this is what you are looking for.
http://www.aroundtheoffice.com/XL-121/products/4461/

OFF 7 8 9 X (Divide)
Sq.Root 4 5 6 - (Mrc)
% 1 2 3 + (M-)
ON (Red) 0 . = (M+)

Unisonic Calculator Ribbon XL 1267 We supply Calculator Ribbon supplies for various calculators, as well as supplies for typewriters, cash registers, printers and dictation equipment. Can't find the calculator supplies you are looking for here? Then call us at 1-800-816-6855 or email us at [email protected] We carry many of the hard to find calculator ribbons for various model printers.

I have an old Unisonic 9725, and the programming method for that phone may work for yours.
1. take handset 'off hook'
2. press: store
3. enter phone no.
4. press store
5. press memory button 1, 2, or 3...or 0-9
6. put handset back 'on-hook'

to use: take handset off hook, and press the memory number that applies.