Eight times the sum of 5 and a number is less than 56?

Answer 1

Read the question.

Then read it again.

8 times the sum. 8 times the sum of what?

The sum of 5 and a number.

What do you need to find out?

What is the number?

Write a number sentence.

Call the number you need to find 'x'

Since you need to find the sum first, put it in parentheses.

(5+x)

But you're going to multiply the sum by 8.

8*(5+x)

What is 8*(5+x)

Less than 56.

8*(5+x)<56

Guess and go.

x=3

8*(5+3)=8*8=64>56. Too big.

Try 2.

8*(5+2)=8*7=56=56. But we want less than 56. Too big.

try 1.

8*(5+1)=8*6=48<56. Yes!

The answer is 1!

Of course, this assumes that the answer is an integer. If not, then x=1.9999999 gives us 8*(5+1.9999999)=8*6.9999999~55.9999992<56. In fact, you could keep on adding 9's to the decimal part and always get an answer just a little bit less than 56.

Don't always assume anything. This question is poorly written and I would give the writer an 'F' for not being more clear. Should the answer be an integer, or is there no answer since we can always add more 9's to the decimal expansion?

Answer 2

45