Skill: Divide decimals by whole numbers

To divide a decimal by a whole number:

1. Estimate the answer.
2. Divide as usual, using the place values in the dividend.
3. Place the decimal point in the quotient directly above the decimal point in the dividend.
4. Multiply to check your answer.

Example: $8.4 \div 4$

Step 1: Estimate.
Since $8 \div 4=2$, the answer should be close to $2$.

Step 2: Divide the whole-number part.
Divide $8$ by $4$:

$$8 \div 4=2$$

Write $2$ in the quotient.

Step 3: Place the decimal point.
Bring the decimal point straight up into the quotient:

$$\begin{array}{r} \phantom{4}2.\\ 4\overline{)8.4} \end{array}$$

Step 4: Divide the tenths.
The $4$ in $8.4$ means $4$ tenths. Divide $4$ tenths into $4$ equal groups:

$$4\text{ tenths}\div4=1\text{ tenth}$$

Write $1$ in the tenths place. Therefore,

$$8.4\div4=2.1$$

Step 5: Check by multiplying.

$$2.1\times4=8.4$$

Because the product matches the dividend, the answer is correct.