Skill: Use order of operations with whole numbers

First, follow the order of operations:

1. Grouping symbols: Work inside parentheses, brackets, or braces. If they are nested, start with the innermost group.
2. Exponents: Evaluate whole-number powers.
3. Multiplication and division: Work from left to right.
4. Addition and subtraction: Work from left to right.

Example:

$$18+\left\{24\div\left[2(3+1)\right]\right\}\times 2^2-5$$

Step 1: Evaluate the innermost grouping.

$$3+1=4$$

Now the expression is

$$18+\left\{24\div[2(4)]\right\}\times 2^2-5$$

Step 2: Finish the grouping.

The expression $2(4)$ means $2\times4$.

$$2\times4=8$$

Now we have

$$18+\{24\div8\}\times2^2-5$$

Step 3: Evaluate the exponent.

The exponent $2$ tells us to multiply $2$ by itself:

$$2^2=2\times2=4$$

Now we have

$$18+\{24\div8\}\times4-5$$

Step 4: Do division and multiplication from left to right.

$$24\div8=3$$

Then multiply:

$$3\times4=12$$

Now the expression is

$$18+12-5$$

Step 5: Do addition and subtraction from left to right.

$$18+12=30$$ $$30-5=25$$

Therefore,

$$\boxed{25}$$

Do not calculate strictly from left to right. Always finish grouping and exponents first, then handle multiplication and division, and finally handle addition and subtraction.