Story Problems: Adding and Taking Away to 100

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What this lesson covers

  • Adding 100 to a one-digit number puts a 1 in the hundreds place.
  • Words in a story tell you whether to add or take away.
  • You can solve a sum with blocks, a number line, a known fact or tens and ones.
  • Some stories need two steps.
Key idea

Adding 100

  • 100 + 7: one hundred and seven, written 107.
  • The 1 goes in the hundreds place. The ones digit stays the same.
SumAnswerSay it
100 + 3103one hundred and three
100 + 8108one hundred and eight
5 + 100105one hundred and five
Key idea

Ways to work it out

  • There is more than one way to solve a sum. Pick the one that fits.
  • Blocks and ten frames let you see the numbers.
  • A number line lets you hop.
  • Splitting into tens and ones keeps the numbers small.
WayExample
Split into tens and ones34 + 25: 30 + 20 = 50, 4 + 5 = 9, so 59
Hop on a number line46 + 20: 56, 66
Use a fact you know6 + 3 = 9, so 60 + 30 = 90
Count back52 − 3: 51, 50, 49
Key idea

Try it: hop to the answer

Worked example

One-step stories

  • Mia has 45 pāua shells. She finds 23 more. How many now? Add: 40 + 20 = 60 and 5 + 3 = 8, so 68.
  • The dairy has 76 iceblocks. 30 are sold. How many are left? Take away 3 tens: 46.
Story wordsSum
finds more, altogether, in totaladd
sold, eaten, left, gave awaytake away
Key idea

Maths blocks

Worked example

Two-step stories

  • 12 kids are on the bus. 5 get off. Then 7 get on. How many now?
  • Do one step at a time. Use the first answer to start the second step.
StepSumAnswer
5 get off12 − 57
7 get on7 + 714

Common mistakes

  • 100 + 6 = 1006
    100 + 6 is one hundred and six, written 106.
  • Taking away when the story says altogether.
    Altogether means put the groups together, so add.
  • Stopping after the first step of a two-step story.
    Do both steps. The first answer is where the second step starts.

Your turn

1

100 + 9 = ?

2

Tama has 54 marbles. He gets 32 more. How many does he have now?

3

There were 85 apples. 40 were eaten. How many are left?

4

15 birds sit on a fence. 6 fly away, then 4 more land. How many birds now?

5

Ana has 8 stickers. She gets 9 more, then gives 5 away. How many does she have?

Show answer

1. 109 2. 86 3. 45 4. 13 5. 12

Summary

What to take away

  • 100 + a one-digit number: put a 1 in the hundreds place.
  • Story words tell you to add or take away.
  • Choose a way that keeps the numbers easy.
  • Two-step stories: one step at a time.
Report a mistake

More in Number

Numbers to 120: Read, Write and CompareNotesGroups of Ten and Where Numbers Sit on a LineNotesRounding, Skip Counting, Odd and EvenNotesAdding and Taking Away: Facts to 20 and TensNotesStory Problems: Adding and Taking Away to 100NotesTimes and Share: 2s, 5s and 10sNotesHalves, Thirds and QuartersNotesComparing Fractions and Finding the WholeNotesNZ Coins and Notes: Count and Make MoneyNotes

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