2/2 divided by 2/2 = 1
4 - 4/4 = 4 - 1/1 = 4 - 1 = 3
1 = 4/4
You don't need two 4-to-1 multiplexers. You only need one 4-to-1 multiplexer, and something that functions as a 2-to-1, like a single 2-input OR gate with one input grounded.
Think of either using or not using the numbers 1 and 4 for each digit. For example, let ____ ____ _____ ____ be the 4 digit number, now 1 can either go in to the first spot or 4 can. So there are 2 choices for that spot, and similarly two for the next spot and the next and the last. So there are 2^4 =16 combinations of 1 and 4 if we make 4 digit numbers. (this uses the multiplication rule) To help a little more to see it, look at just the two digit number, It should have 2^2=4 choices by the logic above. Here they are: 11,14,41,44 and that's it!. See how we had two choices for each digit?
(4 - 4) - 4/4 equals - 1.
4-4+1
two sides are 4 and two are 1 4+4+1+1=10=perimeter 4*1=4=area
two that make 39 their difference is 11
Using exponentials (one squared equals 1): 1² x 4 = 4
To get 24 using 1 3 4 and 6 once you do 6 times 4
you minus 1 =4-1 =3
Design and draw a combinational circuit using AND-OR-NOT gates that accepts 4 input bits, and produces two bit output; the first of the two bits is set to 1 if the number of 1's in the input is even; and the second of the output bit is set to 1 if the input have 3 or more (all four) 1 bits.