Question

how many significant figures are in this number ? 0.40001

Explanation:

Step1: Recall significant figure rules

Leading zeros are not significant. Non - zero digits and zeros between non - zero digits are significant.

Step2: Analyze the number 0.40001

The leading zero (the zero before 4) is not significant. The digit 4 is significant. The zeros between 4 and 1 (the three zeros) are significant. The digit 1 is significant. So we count 4, 0, 0, 0, 1.

Answer:

5