Rounding of numbers is a mathematical operation which allows to reduce the number of figures in number, replacing it with approximate value. Rounding of numbers is applied to convenience when calculating. There is no wish to be confused and stuff himself the head with numbers which have after a comma five figures, and even more. There are several rules of rounding of numbers:
Instruction
1. If the first figure which you want to reject is more or is equal 5, then the last figure which remains - increases by unit. Example: let's take number 25.274 and we will round it to the tenth. The first rejected figure - 7, more than 5, so the last kept figure - 2 increases by unit. I.e., the rounded number - 25.3 turns out.
2. If the first figure which you are going to reject, less than 5 then increase in the last kept figure does not occur. Example: 38.436 we will round to the tenth. The first figure which we want to reject - 3 less than 5, so the last kept figure - 4 does not increase. There is a rounded number - 38.4.
3. If the figure which we want to reject is equal 5, but behind it there are no significant figures, then the last kept figure remains invariable if it even and if odd, then increases by unit. Example 1: there is number 42.85, will round it to the tenth. We reject figure 5, and since behind it there are no significant figures, and the last kept figure 8 - even, it remains invariable. I.e., we receive number 42.8. Example 2: we will round number 42.35 to the tenth. The rejected figure 5, has for itself no significant figures, but the last kept figure 3 - odd, it, respectively, increases by unit and becomes even. We receive 42.4.