Answer is: proper number of significant figures is 25190.00.
10⁴ = 10×10×10×10.
10⁴ = 10000.
1) 4.659×10⁴ = 4.659×10000.
4.659×10⁴ = 46590.
2) 2.14×10⁴ = 2.14×10000.
2.14×10⁴ = 21400.
3) 4.659×10⁴ - 2.14×10⁴ = 46590 - 21400.
4.659×10⁴ - 2.14×10⁴ = 25190 (2.519×10⁴).
An integer is a number that can be written without a fractional component.