this mean case numbers between 400 and 500 e.g. at the start of March:
The key points you need to know from today is NPHET briefing
Any number between 20 and 22.36
500
456
453
400
How about 450
102
400 of them.
432, 468
To find a number that, when squared, gives a result between 400 and 500, we can look for the square roots of these boundary numbers. The square root of 400 is 20, and the square root of 500 is approximately 22.36. Therefore, any number between 20 and about 22.36 will satisfy the condition, such as 21 or 21.5.
400 to 500
Assuming the question is the wrong way round, and meant to read 'between 400 and 500', then 441 = 21 x 21 484 = 22 x 22 as there are many under 400 and an infinite number over 500.