i usually subscribe this weekly newsletters https://swagtimus.substack.com/p/starknet-roundup-32

_This answer was originally posted on [StarkNet Discord](https://www.newton.so/view?tags=discord)_

Newton

does anyone know of newsletters that focus on StarkNet or the zk ecosystem in general?

_This question was originally posted on [StarkNet Discord](https://www.newton.so/view?tags=discord)_

Does anyone know of newsletters that focus on StarkNet or the zk ecosystem in general?

How to convert tokens on starknet? Any DEXs AMMs?

Something that isn't on testnet.

Am going through all these projects on the ecosystem page but am coming up with nothing.

Would be nice if there was a DEX/AMM section ... instead of making people go through all those projects one by one to see what they actually do.

I'm up to Magnety ...

_This question was originally posted on [StarkNet Discord](https://www.newton.so/view?tags=discord)_

How to convert tokens on starknet? Any DEXs AMMs?


How can I connect to deployed StarkNet contract using starknetjs?

What is the maximum value a `uint` can store?

I need to understand a couple of things:

1. What is the maximum value `a felt` and `uint` can store?
2. Are the maximum values stored in felt and uint the same?

---
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What is the maximum value an uint and felt can store in Cairo Language?

Hi everyone,

When i try to invoke my functions with arguments from my frontend app using starknetjs, i get error invalid character, which i presume is an issue from my function accepting felt, but i'm passing texts. Is there any way to convert to felts from the browser or does starknetjs do this by default?

Anyone knows how i can solve the error?

_This question was originally posted on [StarkNet Discord](https://www.newton.so/view?tags=discord)_

How to fix invalid character error while invoking starknetjs frontend app in Cairo?

does cross-chain bridge produce its own block? or it only verify the blocks from A/B chain?

_This question was originally posted on [StarkNet Discord](https://www.newton.so/view?tags=discord)_

Does cross-chain bridge produce its own block? Or it only verify the blocks from A/B chain?

How does Argent X wallet estimate fees in Starknet before sending a tx?

Hello! This is day 15 of the 17 days of the Cairo Challenge. And I have no idea how to solve the [playground](https://www.cairo-lang.org/playground/) exercise “SHARP”.  Perhaps you can help me?

```
// The program below lets you choose a number `x` and output its square `y = x*x`
// (proving that you know the square root of `y`).
//
// 1. Replace "YOUR_NUMBER" with a value of your choice, run the program and
//    make sure you get the expected output (the square of the value you chose).
//
// Take a look at the output line saying "Program hash: ...".
// The program hash is the (Pedersen) hash of the compiled program.
//
// 2. The compiled program does not include the [hints](https://cairo-lang.org/docs/how_cairo_works/hints.html),
//    so changing any code within a hint does not change the resulting program
//    hash.
//    Try changing `x` to a different number and note that the program hash remains
//    unchanged after rerunning.
//
// The Cairo SHARP collects several programs and creates a proof that they ran
// successfully. Such a batch of programs is called a "train".
// Note that it may take a while until a train is created, as the service waits
// to collect enough programs (after a certain amount of time, the train will
// be dispatched, even if it's not full).
//
// 3. Click on "Prove with SHARP" to prove the program using the shared proving service.
//
// After the proof is created, SHARP sends it to an [Ethereum goerli contract](https://goerli.etherscan.io/address/0xAB43bA48c9edF4C2C4bB01237348D1D7B28ef168).
// For each job in the train, a corresponding fact is registered on the contract,
// attesting to the validity of the run with its particular output.
//
// 4. You can monitor the status of your job, using the link in the output pane.
//
// For each job, the corresponding fact is computed as follows:
//   keccak(program_hash, keccak(program_output))
// where:
// * program_hash is the hash of the compiled program, which you can find in
//   the output pane (32 bytes).
// * program_output is the output of the program as a list of 32-byte
//   elements.
//
// For example, if you chose x=3, the output will be [9] and you can compute
// the fact in Python using:
//
//   from web3 import Web3
//
//   program_hash = 0x114952172aed91e59f870a314e75de0a437ff550e4618068cec2d832e48b0c7
//   program_output = [9]
//   Web3.solidityKeccak(['uint256', 'bytes32'], [
//     program_hash,
//     Web3.solidityKeccak(['uint256[]'], [program_output])
//   ])
//
// You can also find your job's fact in the SHARP tracking page you opened
// in step 4.
//
// 5. Once you see that the fact is registered, you can call the
//    [contract's isValid() method](https://goerli.etherscan.io/address/0xAB43bA48c9edF4C2C4bB01237348D1D7B28ef168#readContract) to make sure it's indeed registered.

%builtins output

from starkware.cairo.common.serialize import serialize_word

func main{output_ptr: felt*}() {
    alloc_locals;
    local x;
    %{ ids.x = YOUR_NUMBER %}

    serialize_word(x * x);
    return ();
}
```

---

> Answers to this question are a part of the ✨ 17 days of Cairo Lang with Playground & Newton. ✨
> 

*Vote for your favorite answer - the best answer will win a $10 award. A new day – a new reward! During the next 17 days, our goal is to attract more developers to the Cairo language and to systematize the knowledge of Cairo lang. [Read rules](https://www.notion.so/17-days-of-Cairo-Lang-with-Newton-550dfcda6a2d449ca468be293c776578)*

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Does anyone know of newsletters that focus on StarkNet or the zk ecosystem in general?

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