How many significant figures are present in the following?
$(i)$ $0.0025$ $(ii)$ $208$ $(iii)$ $5005$ $(iv)$ $126,000$ $(v)$ $500.0$ $(vi)$ $2.0034$

$(i)$ $0.0025$: There are $2$ significant figures (leading zeros are not significant).
$(ii)$ $208$: There are $3$ significant figures (zeros between non-zero digits are significant).
$(iii)$ $5005$: There are $4$ significant figures (zeros between non-zero digits are significant).
$(iv)$ $126,000$: There are $3$ significant figures (trailing zeros in a number without a decimal point are not significant).
$(v)$ $500.0$: There are $4$ significant figures (trailing zeros in a number with a decimal point are significant).
$(vi)$ $2.0034$: There are $5$ significant figures (zeros between non-zero digits are significant).