Naomi's square bedroom has an area of 90 square feet. What is
the length of one of the walls? Round to the nearest tenth if
necessary. ( The answer is 9.5 but how to you get there ?)

Think of a number, that when multiplied with itself, will get you 90.

We could try something like 7. So 7*7 = 49, but it's too small.

How about 10? Well we get 10*10 = 100 which is too big. The answer is between 7 and 10.

Let's try 8. So we get 8*8 = 64 which is too small.

This process is repeated until you determine that the answer is somewhere between 9 and 10

9*9 = 81

10*10 = 100

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From here, we can try 9.5 since it's right between 9 and 10

9.5*9.5 = 90.25

close but not quite there. It's a bit too large. So the actual value is somewhat smaller than 9.5

Let's try 9.4

9.4*9.4 = 88.36

That seems even worse off compared to 90.25, so 9.5 is the better answer.

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As a shortcut, you can use the square root on your calculator