It is 640 because 4 is less than 5
It is 600It is 600It is 600It is 600
It is 644 because .4 is less than .5
The answer will depend on the degree to which the number is rounded. Without any indication of that, it is not possible to answer the question sensibly.
It is 644 because .4 is less than .5
644
600
601, 625, 640, 644, 649
1288
For the values: 46 and 28 the LCM is: 644
You do not need to estimate. The answer is exactly 644.
All multiples of 644, which is an infinite number.