Skill: Divide decimals by decimals

To divide by a decimal, make the divisor a whole number. Multiply both the dividend and divisor by the same power of $10$. This keeps the quotient unchanged.

Example: Find $3.75 \div 0.15$.

1. Estimate first.
   Since $3.75 \approx 4$ and $0.15 \approx 0.2$, the answer should be around $4 \div 0.2=20$.

2. Make the divisor a whole number.
   The divisor, $0.15$, has two digits after the decimal point, so multiply both numbers by $100$:

$$3.75 \div 0.15 = 375 \div 15$$

3. Divide.

   • $15$ goes into $37$ two times. Write $2$.
   • $2\times 15=30$, and $37-30=7$.
   • Bring down the $5$ to make $75$.
   • $15$ goes into $75$ five times. Write $5$.

   Therefore,

$$375\div 15=25$$

So,

$$\boxed{3.75\div 0.15=25}$$

The answer makes sense because $25$ is reasonably close to the estimate of $20$.