Question

What numbers does the square root of 355 fall between?

Answer 1

The answer is c)18 and 19.

Let's go through all choices:
a) 15 and 16 is not correct because √355 > 16 > 15: 
15 = √15² = √225
16 = √16² = √256
√355 > √256 > √225   ⇒ √355 > 16 > 15

b) 17 and 18 is not correct because √355 > 18 > 17: 
17 = √17² = √289
18 = √18² = √324
√355 > √324 > √289   ⇒ 19 > √355 > 18

c) 15 and 16 is correct because : 
18 = √18² = √324
19 = √19² = √361
√361 > √355 > √324  ⇒ 19 > √355 > 18

d) 20 and 21 is not correct because 21 > 20 > √355: 
20 = √20² = √400
21 = √21² = √441
√441> √400> √355 ⇒ 21 > 20 > √355