Subtraction (Counting on) — Let's Practise!

Subtraction (Counting on) — Let's Practise! exercise

• How would we solve this problem using counting on?

  Hints

  The first step is to find the subtraction equation you are trying to solve.

  You can then turn the subtraction equation into an addition equation.

  Count on to find the answer before filling it in.

  Solution

  1. Start with a subtraction equation: 28 - 14 = __
  2. Flip it to make an addition equation: 14 + __ = 28
  3. Count on to find the answer.
  4. Fill in the correct answer: 14 + 14 = 28

  Therefore, 28 - 14 = 14

• How many bolts will Mr Squeaks have left?

  Hints

  What is the subtraction equation you are trying to solve?

  The subtraction equation is 46 - 33 = ?.

  How can this be made into an addition equation?

  We can change this to 33 + __ = 46.

  Count on from 33 to reach 46.

  Solution

  The subtraction equation being solved is 46 - 33 = ?.

  We can flip this to 33 + __ = 46.

  Count on from 33 to 46.

  33 + 13 = 46

  46 - 33 = 13

• Can you solve these subtraction problems?

  Hints

  Count on from the smaller number to the larger number.

  Double check your answers by subtracting the smaller number from the larger number.

  Solution

  1.) 24 - 11 = ?

  11 + 13 = 24

  24 - 11 = 13

  2.) 54 - 37 = ?

  37 + 17 = 54

  54 - 37 = 17

  3.) 68 - 35 = ?

  35 + 33 = 68

  68 - 35 = 33

• What is the missing number?

  Hints

  If you are solving an addition equation, count on from the smaller number to the larger number.

  If you are solving a subtraction equation, you can flip it into an addition equation and then count on to solve.

  Perform the inverse, or opposite, operation to check your answers.

  Solution

  27

  • 61 - 34 = 27
  • 84 - 57 = 27
  • 29 + 27 = 56

  31

  • 60 - 29 = 31
  • 84 - 53 = 31
  • 25 + 31 = 56

  43

  • 94 - 51 = 43
  • 32 + 43 = 75
  • 61 - 18 = 43

• How many pieces of cheese are left?

  Hints

  The subtraction equation we are trying to solve is 20 - 9 = ?.

  We can flip this to 9 + __ = 20.

  Count on from 9 to 20.

  Use this number line to help you.

  Solution

  Mr Squeaks has 11 pieces of cheese left.

  20 - 9 = ?

  9 + __ = 20

  9 + 11 = 20

  20 - 9 = 11

• Can you solve the problems?

  Hints

  Work out what the subtraction equation is for each problem.

  Flip it to an addition equation and count on to solve.

  For the first question, the subtraction equation is 60 - 11 = ?

  We can flip this to 11 + __ = 60.

  Solution

  1. Sally started counting down to her birthday when there were 60 days to go. Now there are only 11 days to go. 49 days have passed.
  2. The bakery made 98 cheese straws in the morning and sold 76. They have 22 cheese straws left.
  3. Dave has to wash 113 windows in a day. He has done 84 so far and has 29 left to go.