Sixth Grade · Math · week 12

Decimal operations: all four

Add, subtract, multiply, and divide multi-digit decimals fluently using the standard algorithms.

Decimals follow the same operations as whole numbers, with one extra rule for each: line up the decimal points to add or subtract, count decimal places to multiply, and move both decimal points to divide.

To ADD or SUBTRACT decimals, stack them so the decimal points line up in a column, filling empty spots with zeros if needed.

To MULTIPLY decimals, ignore the decimal points and multiply as whole numbers, then count the total decimal places in both factors and place the point that many spots from the right. To DIVIDE, move the decimal point in the divisor to make it a whole number, then move the decimal point in the dividend the same number of places before dividing normally.

📋 For the teacher
Teach it (10–15 min):
  • Have them physically line up decimal points in a column - misalignment is the number-one error source.
  • For multiplication, practice counting total decimal places separately from the multiplying itself - it is two steps, not one.
  • For division, always fix the DIVISOR first, making it a whole number, then shift the dividend point the same number of places.
  • Estimate first by rounding to whole numbers, so a wildly off answer gets caught immediately.
Talk about it:
  • Why must decimal points line up for adding and subtracting but not for multiplying?
  • How do you know how many decimal places go in a multiplication answer?
  • Why do we move both decimal points the same number of places when dividing?

Mastery looks like: They accurately add, subtract, multiply, and divide decimals and check answers with a quick estimate.

Common stumbles: Forgetting to line up decimal points when adding or subtracting; miscounting decimal places in multiplication; forgetting to move the dividend point in division.

See it visually

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

MultiplicationEqual groups and arrays make products finally click.try →DivisionShare fairly and build equal groups.try →SubtractionTake away and count back, step by step.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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