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Estimate √62

Step by step, with the reason for every step · Estimating square roots · Foundations

Step by step

The question

Question: estimate √62.

√62

The square root of 62 is the number that times itself makes 62.

√62 × √62 = 62

Careful!

The square root is not half.

31 times 31 is 961, far more than 62.

Careful: not √62 = 31 ✗

1 List the squares

First, the square numbers near 62.

6 times 6 is 36.

7 times 7 is 49.

8 times 8 is 64.

9 times 9 is 81.

2 Find where it fits

62 is between the squares 49 and 64.

= 49 < 62 < 64

A bigger number has a bigger square root.

So √62 is between √49 and √64.

= √49 < √62 < √64

√49 is 7.

√64 is 8.

So √62 is between 7 and 8.

= 7 < √62 < 8

3 Which is closer

62 is 13 more than 49, and 2 less than 64.

= 62 − 49 = 13, 64 − 62 = 2

2 is less.

So 62 is closer to 64, and √62 is closer to 8.

2 < 13: closer to 64

So √62 is between 7 and 8, closer to 8.

= 7 < √62 < 8, closer to 8

4 Check

Let's check with the number halfway: 7.5.

7.5 times 7.5 is 56.25, less than 62.

7.5 × 7.5 = 56.25 < 62

So √62 is above 7.5: closer to 8.

The answer is right!

√62 > 7.5: closer to 8

Let's look back.

First: list the squares.

Then: find where it fits.

Then: which is closer.

Last: check.

Answer
= 7 < √62 < 8, closer to 8

Your turn

Try this one yourself, then check:

Estimate √57
Show the answer
7 < √57 < 8, closer to 8

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