ANSWER: 40
EXPLANATION:
1) 40.73 to 1 significant figure = 40.
2) 1.06 to 1 significant figure = 1.
3) Therefore, we just multiply 40 by 1, which equals 40.
FURTHER EXPLANATION (IF NEEDED):
With significant figures, whole numbers such as 10, 20, 50 etc. have 1 significant figure. This is because the 0 does not count as a significant figure.
With decimals, all numbers after the decimal point are also included as significant figures (even 0). E.g. 40.73 has 4 significant figures and 1.06 has 3 significant figures.
EXAMPLES (IF NEEDED):
Rounding to 2 significant figures:
Rounding to 3 significant figures:
Rounding to 4 significant figures:
E.g. 1006 has 4 sig figs, while 1060 would have 3 sig figs because the last 0 is not counted as a significant figure. 10.60 would have 4 sig figs because of the decimal.