Integers ending in a string of zeros are ambiguous. You cannot tell whether this number is accurate to the nearest hundred million (1 significant figure), to the nearest million (3 sf) or even the nearest unit (9 sf).
It has 1 significant figure.
400000000
400000000
2000-400000000 = -399998000
400000000
400000000
231.57 has five significant figures/numbers. All the numbers in 231.57 are significant.
Answer: 400,000,000 m = 1,312,335,958.005 '
400000000
0.028 x 400000000 = 11200000
The figure 18.03 has a total of four significant numbers
20000000 x 20 = 400000000