What do zeros in front of a number signify in significant figures?

Zeros in front of a number are considered non-significant in terms of significant figures. This is because they serve to place the decimal point and do not contribute to the precision of the measurement itself. For instance, in the number 0.0045, the leading zeros (the three zeros before the digit '4') are merely placeholders and indicate that the actual significant figures start from the '4'. Hence, the significant figures in this case are '4' and '5', which totals to two significant figures. The inclusion of leading zeros doesn't alter the actual value of the number, which remains as 0.0045. This principle assists in clearly communicating the precision of a measurement in scientific contexts as well.