Yes - often there are two buttons labelled "C", and "CE". "CE" (clear entry) will delete the last number, while "C" will clear the entire calculation. Details, of course, may vary among different models of calculators.
some people are used to using the bottom right one as a calculator
Yes, You wouldn't be able to do too much with a calcultor with no buttons...
by buttons.....
12
adding
CA on an electronic calculator usually stands for "Clear All" or "Clear All Entries." Pressing the CA button will clear all calculations or data stored in the calculator's memory. It essentially resets the calculator to its starting state.
clear
1, 2 and + are 3 buttons.
AC stands for all clear on a calculator
All Clear
all clear