Question

How many significant digits are in the number 0.00120?

Answer 1

`3`

Explanation:

The initial "`0.00`" determines the magnitude of the number, but its precision is implied by the number of following digits, namely `3` in "`120`".

In scientific notation we would write:

`0.00120 = 1.20 xx 10^(-3)`

Answer 2

Three significant digits (i.e. `120`).

Explanation:

In any number figure, the number of digits in the figure that are important in determining its value are called significant.

Zeros are included only if they contribute to the value of the number. Zeros before the first significant digit, if to the left of decimal point are ignored and similarly zeros to the right of number after decimal point are not included. Leading zeros are not significant but trailing zeros, those to the right of the last non-zero digit, are significant.

For example, in the number `50600`, we have all the five significant digits. However, had it been `00050600`, first three zeros would have been ignored and similarly in `50600.00` last two zeros are not significant.

Hence, in `0.00120`, we have three significant digits (i.e. `120`).