Decimals
| Add or subtract | Line up the decimal points (fill with zeros): 12.5 + 3.75 = 12.50 + 3.75 = 16.25. |
| Multiply | Multiply as whole numbers, then count the decimal places in both: 0.3 × 0.04 → 3 × 4 = 12, three places → 0.012. |
| Divide | Move the decimal in both numbers until the one you divide by is whole: 7.2 ÷ 0.08 = 720 ÷ 8 = 90. |
| Times or divided by 10, 100, 1,000 | Move the point one place per zero: 3.6 × 100 = 360; 3.6 ÷ 100 = 0.036. |
| Place value | In 4,827.395: 4 thousands, 8 hundreds, 2 tens, 7 ones, 3 tenths, 9 hundredths, 5 thousandths. |
AFOQT questions on this: Place value · Decimals to fractions · Scientific notation