How to develop a neural network which can perform subtraction?
It is an easy task. Make some training data, two inputs and one output. this is a regression task. You can train a simple
MLP or you can employ
RNNs such as
LSTM for this task. Take a look at here.
Yes, there has been recent research on this that makes this task more efficient than feeding it in an RNN.
There are implementations in multiple libraries.