how many significant digits are in the following measurement

2.546m

To determine the number of significant digits in a measurement, follow these rules:

1. All non-zero digits are significant. In this case, the digits 2, 5, 4, and 6 are non-zero.

2. Zeros between non-zero digits are significant. The zero between 5 and 4 is between non-zero digits, so it is significant.

3. Leading zeros before the first non-zero digit are not significant. However, trailing zeros after the last non-zero digit are significant if there is a decimal point present.

In the measurement 2.546m, there are four significant digits because all the digits in the number are non-zero.