Yes, we can update the program to work on text input with basic mathematical operations. Here's an example implementation:

```python 
class Calculator:
def init(self):
pass

def evaluate(self, expression):
    tokens = expression.split()
    stack = []
    i = 0
    while i < len(tokens):
        if tokens[i].isdigit():
            stack.append(float(tokens[i]))
        else:
            if tokens[i] == '+':
                a = stack.pop()
                b = stack.pop()
                stack.append(a + b)
            elif tokens[i] == '-':
                a = stack.pop()
                b = stack.pop()
                stack.append(b - a)
            elif tokens[i] == '*':
                a = stack.pop()
                b = stack.pop()
                stack.append(a * b)
            elif tokens[i] == '/':
                a = stack.pop()
                b = stack.pop()
                stack.append(b / a)
        i += 1
    return stack.pop()
```

**Example usage:**
```python
c = Calculator()
print(c.evaluate('2 + 10 / 5')) # Output: 4.0
print(c.evaluate('3 * 9 - 7')) # Output: 20.0
```
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