Keeping the single-digit numbers from 1 through 7 in order, as shown here, it is possible to insert three plus and/or minus signs to obtain the number 79. 1 2 3 4 5 6 7 123 45 6 + 7 = 79 Notice that not filling in the blanks between 1, 2, 3 produces the number 123. Similarly, not filling in the blank between 4 and 5 produces the number 45 or, the blank space given in the drop-down list can be used to form a two-digit or a three-digit number. How can three plus and/or minus signs be inserted between the following numbers to obtain the number 2