Comparison

Co vs Addition Algorithms

Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.

Head to head
About

Co

This app provides advanced word prediction and spelling support for students. It offers grammar-smart suggestions and access to millions of topic-specific dictionaries to aid in writing. Built-in text-to-speech functionality helps users review their work.

Highlights
  • Grammar-smart word prediction
  • Millions of topic-specific dictionaries
  • Flexspell™ technology for spelling errors
  • Built-in text-to-speech
  • Personalized vocabulary and settings
Features
Read full description

Co:Writer® Universal app and third-party keyboard gives students easy access to word prediction on iPad, iPad Pro, iPhone, and iPod Touch. Students simply sign in to their Co:Writer Universal accounts to write with their personal settings and vocabulary. ABOUT CO:WRITER UNIVERSAL This version is for schools with a Co:Writer Universal license only. Users without a Co:Writer Universal license must purchase the Co:Writer app. HOW DOES CO:WRITER WORK? As letters are typed, Co:Writer predicts the intended word with a selection of word suggestions using powerful grammar-smart word prediction. These suggestions can be read aloud with a swipe. Selecting the intended word places it into the writing document. For feedback while writing (and after writing) built-in text to speech can be used to read letters, words, sentences, and the entire document. 4+ MILLION TOPIC-SPECIFIC DICTIONARIES Co:Writer has access to a main prediction dictionary (that includes core words) and Topic Dictionaries (that includes topic specific words). Co:Writer can access over 4 million topic-specific dictionaries which are activated based on the writing task. A small sampling of the variety of topic dictionaries: - America's Cup - Apple II - Compare and Contrast - Dinosaurs - Grumpy Cat - History of the Peloponnesian War - Mahatma Gandhi - My Dog - Pig Latin - Rolls-Royce Silver Ghost - SpongeBob SquarePants - Tommy (album) - Wonders of the World SPELLING SUPPORT Co:Writer handles the widest range of spelling mistakes through its Flexspell™technology including phonetic spelling and inventive spelling errors (letter omissions, word ending omissions, letter reversals, etc). Examples of how Co:Writer aides with phonetic and/or inventive spelling: Before Co:Writer The blk jargon flu over the bra lfnt. R u hpy to ce me? I no hw to nor the fone. After Co:Writer The black dragon flew over the gray elephant. Are you happy to see me? I know how to answer the phone. GRAMMAR SUPPORT Co:Writer bases its prediction off of proper grammar, and uses its understanding of grammar to accurately predict words within the framework of valid sentence structures. Examples of how Co:Writer aides with grammar: Dogs are furry. (noun, verb, adj.) - When you typed d-o, you get plural noun choices Three very mangy dogs ran down the street. (adj., adv., adj., noun, verb… etc.) - After typing three, very, mangy, you get plural noun choices, then you get plural verb tenses. OTHER FEATURES - Built-in Text to Speech - Export

About

Addition Algorithms

Read full description

The Addition Algorithms app introduces students to a research based approach to solving addition problems. It steps students through the two different procedures for adding multi-digit numbers This app challenges the player to find the answer to a multi-digit addition problems. Completing the activities involves placing digits into the cells of a grid showing the steps of the selected algorithm. The Addition Algorithms app is designed to be a quick math exercise that teachers can use to provide practice in problem solving. Special sound effects make the game fun to use and the interactive design facilitate problem solving strategies.

Screenshots

Co4 screens

Verdict

The call

The clearest difference is price: Co at Free against Addition Algorithms's $0.99. Co also leads on update cadence (every 4 months vs every 18 months) and iOS requirement (10.0 vs 12.0). On ads, in-app purchases and device support there is nothing between them.

Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS

CostPrice · In-app purchases · Ads · Monetization

Co is free to download; Addition Algorithms costs $0.99 up front. Neither carries in-app purchases, so what you see is what you pay.

UpkeepUpdate frequency

Co ships an update every 4 months, Addition Algorithms every 18 months. The most recent releases landed on June 5, 2026 and September 15, 2026 respectively.

Scorecard3 real differences · 7 level
Co versus Addition Algorithms: the parameters behind the verdict, then further details
ParameterCoAddition Algorithms
PriceFree — better$0.99
Rating2.6 (17 ratings) — better—
Positive reviews8.3% of reviews—
Number of ratings17 — better—
Update frequencyEvery 4 months — betterEvery 18 months
AdsNoNo
In-app purchasesNoNo
MonetizationFree—
DevicesiPhone, iPad, iPod — betteriPad, Mac
Requires iOS10.0 — better12.0
Further details — not scored
Size45 MB23 MB
Age rating4+4+
DeveloperDon Johnston IncorporatedVentura Educational Systems

In-app purchases

None

Co

No in-app purchases

None

Addition Algorithms

No in-app purchases

Questions

Is Co free?
Co is free to download, with no in-app purchases.
Is Addition Algorithms free?
Addition Algorithms costs $0.99, with no in-app purchases.
Do Co or Addition Algorithms have ads?
Neither Co nor Addition Algorithms shows ads.
Which is updated more often, Co or Addition Algorithms?
Co ships an update every 4 months, and Addition Algorithms every 18 months. Most recently, Co was updated on June 5, 2026 and Addition Algorithms on September 15, 2026.

Other comparisons