Lesson · M.3.1
Decimal place value, adding and subtracting
Read decimal place value correctly and add or subtract decimals without a calculator, the way the HESI A2 math section expects.
ObjectiveM.3.1Read5 minExam weightDecimals ≈ 18% of Mathematics
This lesson is part of the full Study Guide
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- Name the place value of any digit to the left or right of a decimal point.
- Line up decimal points correctly before adding or subtracting, including whole numbers with no visible decimal.
- Add and subtract multi-digit decimals with regrouping, without a calculator.
What the lesson concludes
- Every place right of the decimal point is ten times smaller than the one before it: tenths, hundredths, thousandths, in that order.
- A whole number with no decimal point still has one. Write it in before you line anything up.
- Decimal points must stack directly above one another. If they do not, the addition or subtraction is wrong before you even start.
- Pad missing digits with zeros rather than leaving blanks, so every column has something to add or subtract.
- Regrouping across a decimal point works exactly like regrouping with whole numbers. The decimal point never moves.