Question

A broken calculator can double any number or permute its digits (but 0 cannot go up front). Can we start with number 1 and obtain 78 by a series of these operations

Answer 1

Answer: it's impossible to obtain 78

Step-by-step explanation: Since the calculator can double any number or permute its digits except 0 

starting with number 1 

1, 2, 4, 8, 16, 32, 64, 128

Therefore, it's impossible to obtain 78 by a series of these operations