Text improvements

21.md

@@ -96,13 +96,13 @@ In another particular case, when the user is denominating the amount in millisat
 + <callback><?|&>amount=<millisatoshi>&convert=<CURRENCY>
 ```
 
-Note that the amount provided in all requests is always in integer number denominated in the smallets possible unit of the selected currency. The smallest unit need to be um sync with the `displayDecimals` parameter, so the `WALLET` has all the needed information to receive input and show output properly.
+Note that the amount provided in all requests is always an integer number denominated in the smallets possible unit of the selected currency. The smallest unit need to be in sync with the `displayDecimals` parameter, so the `WALLET` has all the needed information to receive input and show output properly.
 
 ### Service-side second response
 
 Upon receiving a currency denominated request from `WALLET`, the `SERVICE` must return a lightning invoice with an amount matching the converted rate from currency. The rate does not need to be the same as provided on the first response.
 
-If the `WALLET` requested an actual conversion, the `SERVICE` must provide an additional field alongside the invoice informing the guaranteed `converted` amount that will be credit to the receiver upon payment. The `converted` amount, and therefore the conversion rate, must be guaranteed by the `SERVICE` for as long as the lightning invoice is not expired.
+If the `WALLET` requested an actual conversion, the `SERVICE` must provide an additional field alongside the invoice informing the guaranteed `converted` amount that will be credit to the receiver upon payment. The `converted` amount, and therefore the conversion rate, must be guaranteed by the `SERVICE` for as long as the lightning invoice is not expired. The `converted` amount must be denominated in the smallest unit of the currency, just like the `amount` parameter.
 
 ```typescript
 type BaseResponse = {