Skill: Use compatible numbers with decimals

Compatible numbers are numbers that are close to the original numbers or equivalent to them, but make the operation easier.

For division, you can multiply both the dividend and divisor by the same power of $10$. This keeps the quotient the same.

Example: Find $7.2 \div 0.8$.

1. Both numbers have one digit after the decimal point. Multiply both by $10$ to remove the decimals:

$$7.2 \div 0.8 = 72 \div 8$$

2. Divide:

$$72 \div 8 = 9$$

3. So,

$$7.2 \div 0.8 = 9$$

The numbers $72$ and $8$ are compatible numbers because they make the division easy while keeping the value of the quotient unchanged. Always change both numbers in the same way so the operation stays equivalent.