Video Transcript
Insert the appropriate symbols from
addition, subtraction, multiplication, and division to make the calculation
correct. Eight blank 0.5 blank 40 equals
28.
We could answer this question by
trial and error by substituting each combination of the four symbols in turn. An alternative method would be to
initially consider the order of operations and acronym PEMDAS. Parentheses and exponents will not
be relevant for this question, as we’re only allowed to use addition, subtraction,
multiplication, and division. It’s important to recall that
multiplication and division, along with addition and subtraction, have equal
precedence. However, any multiplication or
division calculation must be done prior to any addition or subtraction.
We might initially notice in our
calculation that the right-hand side is equal to 28, and our first number is
eight. We know that eight plus 20 equals
28. This suggests that the first
missing symbol could be an addition one. 0.5 is the same as one-half, and we
know that one-half of 40 is 20. This means that 0.5 multiplied by
40 is also equal to 20. This indicates that the second
missing sign is a multiplication one.
We can now check to see whether
eight plus 0.5 multiplied by 20 does indeed equal 28. Our first step would be to carry
out the multiplication, 0.5 multiplied by 40. We know this is equal to 20. So we’re left with eight plus
20. Eight plus 20 is indeed equal to
28. The missing symbols in the
calculation are addition and multiplication such that eight plus 0.5 multiplied by
40 is 28.
