Adding and subtracting decimals

The Maths Habit

Who is taller?

You cannot tell yet. Stand them on the same floor first: line them up.

Decimal point
The dot that comes after the ones.
Line up
Put each column under the same column of the other number.
Exchange
Swap ten counters in one column for one counter in the next column.

OnesTenthsHundredths3.471110.10.10.10.10.010.010.010.010.010.010.01+ 1.2510.10.10.010.010.010.010.01TotalCount11110.10.10.10.10.10.10.10.010.01472
  1. Line up the points.Ones under ones, tenths under tenths.
  2. Count each column.7 hundredths and 5 hundredths are 12 hundredths.
  3. Ten in a column swap for one in the next column up.12 hundredths are 1 tenth and 2 hundredths. 3.47 + 1.25 = 4.72

Which column does each digit of 1.25 go in?

1.25 1 ones, 2 tenths, 5 hundredths

Work out 2.43 + 1.36. 3.79

OnesTenthsHundredths2.43110.10.10.10.10.010.010.01+ 1.3610.10.10.10.010.010.010.010.010.01TotalCount1110.10.10.10.10.10.10.10.010.010.010.010.010.010.010.010.01379

Work out 1.58 + 2.24. 3.82

OnesTenthsHundredths1.5810.10.10.10.10.10.010.010.010.010.010.010.010.01+ 2.24110.10.10.010.010.010.01Total111Count30.10.10.10.10.10.10.10.10.010.0182

Work out 2.43 + 1.36. 3.79

OnesTenthsHundredths2.43110.10.10.10.10.010.010.01+ 1.3610.10.10.10.010.010.010.010.010.01TotalCount1110.10.10.10.10.10.10.10.010.010.010.010.010.010.010.010.01379

Work out 3.6 + 1.25. 4.85

OnesTenthsHundredths3.61110.10.10.10.10.10.1+ 1.2510.10.10.010.010.010.010.01TotalCount11110.10.10.10.10.10.10.10.10.010.010.010.010.01485

Work out 2.43 + 1.36. 3.79

OnesTenthsHundredths2.43110.10.10.10.10.010.010.01+ 1.3610.10.10.10.010.010.010.010.010.01TotalCount1110.10.10.10.10.10.10.10.010.010.010.010.010.010.010.010.01379

Work out 1.47 + 2.35. 3.82

OnesTenthsHundredths1.4710.10.10.10.10.010.010.010.010.010.010.01+ 2.35110.10.10.10.010.010.010.010.01Total111Count30.10.10.10.10.10.10.10.10.010.0182

Work out 2.43 + 1.36. 3.79

OnesTenthsHundredths2.43110.10.10.10.10.010.010.01+ 1.3610.10.10.10.010.010.010.010.010.01TotalCount1110.10.10.10.10.10.10.10.010.010.010.010.010.010.010.010.01379

Work out 2.8 + 1.6. 4.4

OnesTenthsHundredths2.8110.10.10.10.10.10.10.10.1+ 1.610.10.10.10.10.10.1TotalCount11110.10.10.10.1440

Work out 2.43 + 1.36. 3.79

OnesTenthsHundredths2.43110.10.10.10.10.010.010.01+ 1.3610.10.10.10.010.010.010.010.010.01TotalCount1110.10.10.10.10.10.10.10.010.010.010.010.010.010.010.010.01379

A pen costs £1.65 and a ruler £2.20. How much together? £3.85

OnesTenthsHundredths£1.6510.10.10.10.10.10.10.010.010.010.010.01+ £2.20110.10.1TotalCount1110.10.10.10.10.10.10.10.10.010.010.010.010.01385

Adding and subtracting decimals worksheet, page 1

4 has no tenths. Swap one 1 counter for counters in the next column down. Which, and how many?

1111 Ten 0.1 counters

Work out 5.46 − 2.23. 3.23

OnesTenthsHundredths111110.10.10.10.10.010.010.010.010.010.01StartLeft323

Work out 4.52 − 1.38. 3.14

OnesTenthsHundredths11110.10.10.10.10.10.010.01StartLeft30.010.010.010.010.010.010.010.010.010.0114

Work out 5.46 − 2.23. 3.23

OnesTenthsHundredths111110.10.10.10.10.010.010.010.010.010.01StartLeft323

Work out 3 − 1.4. 1.6

OnesTenthsHundredths111StartLeft0.10.10.10.10.10.10.10.10.10.1160

Adding and subtracting decimals worksheet, page 2

Answer sheet

Is it right? Thumbs up or thumbs down.

  1. 2.5 + 1.3 = 3.8

    Thumbs up

  2. 4.2 + 1.15 = 5.35

    Thumbs up

  3. 3.5 + 1.25 = 1.60

    Thumbs down: it is 4.75

  4. 5 − 2.3 = 3.3

    Thumbs down: it is 2.7

  5. 6.4 − 1.2 = 5.2

    Thumbs up

  1. Two numbers add up to 1. One is 0.35. What is the other?

    0.65

  2. Ben pays for a £3.45 lunch with a £10 note. How much change?

    £6.55

  3. Make 2 by adding three different decimals.

    For example, 0.5 + 0.7 + 0.8

  1. Work out 2.4 + 1.35. Line up the points.

    3.75

  2. Work out 3.67 + 1.25.

    4.92

  3. Work out 5 − 1.6.

    3.4
Exit tickets to print