Skill: Divide whole numbers by decimals

To divide a whole number by a decimal, find how many groups of the decimal amount fit into the whole number.

Example: Find $6 \div 0.4$.

1. Estimate. Since $0.4$ is less than $1$, the answer should be greater than $6$. In fact, about ten groups of $0.4$ make $4$, so the answer will be around $15$.

2. Make the divisor a whole number. Move the decimal point in $0.4$ one place to the right to get $4$. Because you moved the divisor one place, also multiply the dividend by $10$:

$$6 \div 0.4 = 60 \div 4$$

3. Divide.

$$60 \div 4 = 15$$

So,

$$6 \div 0.4 = 15$$

4. Check by multiplying.

$$15 \times 0.4 = 6$$

The answer is correct because $15$ groups of $0.4$ equal $6$. When the divisor is less than $1$, the quotient can be greater than the whole-number dividend.