def simple(expr: str) -> int:
    """Evaluate a simple expression with no parens.

    >>> simple("3 + 4 * 5")
    35
    >>> simple("1 + 2 * 3 + 4 * 5 + 6")
    71
    """
    # Split into bits then get out if we're done.
    bits = expr.split()
    if len(bits) == 1:
        return int(expr)

    # Evaluate the first three bits.
    a, op, b = bits[:3]
    if op == '+':
        x = int(a) + int(b)
    else:
        x = int(a) * int(b)
    
    # Make a new expression and recurse.
    new_expr = ' '.join([str(x)] + bits[3:])
    return simple(new_expr)