Freeform Calculator is exactly that.
Freeform Calculator works using the same conventions as Excel: multiplication and division occur first, addition and subtraction second. Using brackets ensures certain things are grouped for calculation. It doesn't do scientific calculations or trigonometry or raising numbers to powers, but it does do simple things a whole lot easier and with less fuss than Excel.
You can link to Freeform Calculator and make a shortcut on your home screen or you can get it on Google Play.
This app does not carry ads and has no tricky links to catch you out. If you like it please rate it well and tell others. It was created as a fun project and my reward will be to see that it's popular.
Pass The Bill is another calculator.
Using Pass The Bill on a phone or tablet in a restaurant will remove the stress that often happens when a bill is presented and friends want to pay just for their fair share of the bill. You can calculate what each person should pay based on their individual items and on the items they shared with others. Then you can add tips based on those amounts.
It was a difficult decision whether to call this app "pass the bill" or "parse the bill". Search engines could mistake pass for parse or vice versa, but the word parse has a meaning that properly describes the process as being a separation of the parts into distinct sections - text and numbers.
You can link to Pass the Bill and make a shortcut on your home screen or you can get it on Google Play.
This is another app that does not carry ads and has no tricky links, however, this free version is limited to splitting bills for up to 5 people. If you like it and need more people on the bill you can upgrade to Pass The Bill Premium for a very small cost.
Winning Dice was a little project to see what happens if a gambler plans to make a certain amount of money and increases the bets each time to cover previous losses. Rolling a dice is easy to understand and the true odds of rolling any number are very easy calculate - it's got 6 sides and they all have the same chance of being on top, so that's like 1 to 5 (once for your number and five times for the other numbers). It was quite an eye-opener to see how easy it is to lose a fortune when your number waits a long time before showing.
This is another free app but might show ads if it gets used a lot. If it gets difficult I will do a completely ad-free version now that I have learned enough Android language.