One
231.57 has five significant figures/numbers. All the numbers in 231.57 are significant.
The prime numbers (factors) of 1000 are: 2 and 5
168 prime numbers under 1000.
111 numbers between 5 and 1000 are divisible by 9
1 significant figure.
Both 10 and 1000 are individual whole numbers.
The figure 18.03 has a total of four significant numbers
There are 90 palindromic numbers between 100 and 1000
There are 168 prime numbers between 1 & 1000.
Three. All nonzero numbers are significant, and any zeros in between significant numbers are significant.
Because 10.00400 is 10.004, this has five significant digits (numbers).
There are 1000 - 9 = 991 of them.