Use Grouping symbols, exponents, and symbols for addition, subtraction, multiplication, and division with the digits 1, 9, 8, and 7 (in that order)

Question

Form expression that will yield each value.

 

a. 6    B. 7   c. 9

Answer 1

If you use the absolute-value sign as a grouping symbol, then:

 

|1 ÷ (9 - 8) - 7| = |1 ÷ 1 - 7| = |1 - 7| = |-6| = 6

 

If we write 1 - 9 + 8 + 7,  this equals:

 

-8 + 8 + 7 = 0 + 7 = 7 by the Order of Operations

 

Finally, if we write 1 + 9 - 8 + 7, this equals:

 

10 - 8 + 7 = 2 + 7 = 9 by Order of Operations