Fifth Grade · Math · week 5

Subtract decimals

Subtract decimals with up to thousandths, aligning place value and regrouping across the decimal point when needed.

Subtracting decimals uses the same lineup move as adding: stack the decimal points, fill missing places with zeros, then subtract like whole numbers.

Sometimes you need to regroup across the decimal point, exactly like borrowing across any other place -- just keep careful track of every zero digit as you go.

📋 For the teacher
Teach it (10–15 min):
  • Model with money first (dollars and cents), since borrowing across a dollar already feels familiar.
  • Insist on filling every empty decimal slot with a zero before subtracting a single digit.
  • Walk through regrouping one column at a time, narrating "borrow one, and it becomes ten of the next smaller place."
  • Estimate first by rounding each number, so an answer that is way off gets caught immediately.
Talk about it:
  • Why do you add zeros before subtracting decimals of different lengths?
  • How is borrowing across a decimal point like borrowing between any two whole-number places?
  • How does estimating help you catch a subtraction mistake?

Mastery looks like: They can subtract decimals of different lengths, regrouping across the decimal point as needed, and check with an estimate.

Common stumbles: Subtracting the smaller digit from the larger one in a column no matter its position; forgetting to regroup all the way through a zero.

See it visually

Interactive, spoken-aloud tools that show this idea in motion.

SubtractionTake away and count back, step by step.try →Place ValueWatch ones, tens, hundreds, and thousands build big numbers.try →
Homework for this lessonType it, write it with a stylus, or print it for pencil & paper.open →
Records attendance + 15 min of Math for this learner.
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