root estimation

Which of these is the best approximation for this square root?
Exploring and noticing Working systematically Conjecturing and generalising Visualising and representing Reasoning, convincing and proving
Being curious Being resourceful Being resilient Being collaborative
Without using a calculator, work out which of the following is the best approximation for $$\sqrt{\frac{2001}{10000}}$$

$0.4,$     $0.42,$     $0.45,$     or     $0.47$

This problem is taken from the World Mathematics Championships