Round 3.6 to the nearest whole number.

Step-by-step solution

1. 1

   Identify the two candidates. Rounding to a whole number means choosing between the whole numbers immediately below and above the value. Since $3<3.6<4$, the only candidates are $3$ (round down) and $4$ (round up). Nothing else can be nearest.

2. 2

   Measure the distance to each candidate. This is what 'nearest' literally means:

   $|3.6-3|=0.6,\qquad|3.6-4|=0.4$

   Because $0.4<0.6$, the value $3.6$ sits closer to $4$ than to $3$.

3. 3

   Cross-check with the digit rule. The usual shortcut looks only at the first dropped digit: round up if it is $5$ or more, down if it is $4$ or less. Here that digit is $6\ge5$, so round up — the same verdict as the distance comparison, which is exactly why the shortcut works.

4. 4

   State the answer.

   $3.6\approx4$

   The symbol is $\approx$, not $=$: rounding deliberately discards information, and the discarded amount here is $0.4$.

5. 5

   Watch the boundary case. The distance argument only ties at $3.5$, where both gaps equal $0.5$; the convention 'round half up' then sends it to $4$ as well. Anything from $3.5$ up to $3.999\ldots$ rounds to $4$, and anything from $3.0$ up to (but not including) $3.5$ rounds to $3$.