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Meet bonny and tommy

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Leaner section


Activity: rounding off [lo 1.8, lo 1.10]

  • Get some counters from your teacher. Estimate how many you have. Write down your estimate.

I estimate ____________________________________________________________

  • Now group the counters on the desk in tens and units.
  • Count them and write: I have ______________________________________
  • How was your estimate: too many, too few or just right?

Write: I estimated ________________________________________________

By how many were you out? _____________________________________________

  • Is your number closer to 40, closer to 50 or equally far away from both?

Write: My number is ___________________________________________________

  • How can you make your number equal to 50?

Write: I can add _______________ ____________ + ____________ = 50

  • If you have added 5 or less than 5, 50 is your nearest multiple of ten.
  • How can you make your number equal to 40?

Write: I can subtract _______________ : ____________ - ____________ = 40

  • If you subtracted 4 or less than 4, then 40 is your nearest multiple of ten.
LO 1.8

To round off a number to the nearest ten you must know which multiple of ten is closer to the number. If your number is the same distance from two multiples of ten, we use the greater multiple of ten.

  • Look at the numbers and make an * next to the nearer multiple of ten.
43 40 50
49 40 50
46 40 50
41 40 50
LO 1.10
  • Now help Bonny and Tommy to find the nearer multiple of ten.

Remember: If the units are 5 or more than 5,

we use the greater multiple.

  • If the units are 4 or less than 4, we use the smaller multiple.

24: nearer multiple is 20 16: nearer multiple is 20

37: nearer multiple is _____ 52: nearer multiple is _____

15: nearer multiple is _____ 73: nearer multiple is _____

81: nearer multiple is _____ 94: nearer multiple is _____

  • Round off to the nearer 10. (This will help you to estimate):

If we round off, it helps us to estimate what the answer should be more quickly.

Remember! This is not an accurate answer!

  • Use rounding off and estimate first. Then do an accurate calculation. Write the rounded off number above the number.
  • Tommy has 84c in his purse and buys a banana for 69c.

How much money does he have left?

Rounding off: Number sentence: _____________________________________________________________________

Calculate: Number sentence: _____________________________________________________________________

This will help you to estimate your change when you buy something.

LO 1.10
  • Bonny prefers to do her sums horizontally.
  • Tommy prefers to do his sums vertically.
  • Let’s try both ways and then decide which is the easier.
LO 1.8

Bonny says: Subtraction is a bit different.

  • NEVER rename the first number.

Check your answer: 12 + 64 = 76

  • Like this! He thought like this:
  • Check your answer:

1 2



  • What do you think, do you want to do your sums like Bonny or like Tommy?


LO 1.8


Learning Outcome 1: The learner will be able to recognise, describe and represent numbers and their relationships, and to count, estimate, calculate and check with competence and confidence in solving problems.

Assessment Standard 1.8: We know this when the learner can perform calculations, using appropriate symbols, to solve problems involving:

1.8.1 addition and subtraction of whole numbers with at least 3 digits;

1.8.2 multiplication of at least whole 2-digit by 1-digit numbers;

1.8.3 division of at least whole 2-digit by 1-digit numbers;

  • estimation;

Assessment Standard 1.10: We know this when the learner uses the following techniques:

1.10.1 building up and breaking down numbers;

1.10.2 doubling and halving;

1.10.3 number-lines;

1.10.4 rounding off in tens.

Questions & Answers

what does nano mean?
Anassong Reply
nano basically means 10^(-9). nanometer is a unit to measure length.
do you think it's worthwhile in the long term to study the effects and possibilities of nanotechnology on viral treatment?
Damian Reply
absolutely yes
how to know photocatalytic properties of tio2 nanoparticles...what to do now
Akash Reply
it is a goid question and i want to know the answer as well
characteristics of micro business
for teaching engĺish at school how nano technology help us
Do somebody tell me a best nano engineering book for beginners?
s. Reply
what is fullerene does it is used to make bukky balls
Devang Reply
are you nano engineer ?
fullerene is a bucky ball aka Carbon 60 molecule. It was name by the architect Fuller. He design the geodesic dome. it resembles a soccer ball.
what is the actual application of fullerenes nowadays?
That is a great question Damian. best way to answer that question is to Google it. there are hundreds of applications for buck minister fullerenes, from medical to aerospace. you can also find plenty of research papers that will give you great detail on the potential applications of fullerenes.
what is the Synthesis, properties,and applications of carbon nano chemistry
Abhijith Reply
Mostly, they use nano carbon for electronics and for materials to be strengthened.
is Bucky paper clear?
so some one know about replacing silicon atom with phosphorous in semiconductors device?
s. Reply
Yeah, it is a pain to say the least. You basically have to heat the substarte up to around 1000 degrees celcius then pass phosphene gas over top of it, which is explosive and toxic by the way, under very low pressure.
Do you know which machine is used to that process?
how to fabricate graphene ink ?
for screen printed electrodes ?
What is lattice structure?
s. Reply
of graphene you mean?
or in general
in general
Graphene has a hexagonal structure
On having this app for quite a bit time, Haven't realised there's a chat room in it.
what is biological synthesis of nanoparticles
Sanket Reply
what's the easiest and fastest way to the synthesize AgNP?
Damian Reply
types of nano material
abeetha Reply
I start with an easy one. carbon nanotubes woven into a long filament like a string
many many of nanotubes
what is the k.e before it land
what is the function of carbon nanotubes?
I'm interested in nanotube
what is nanomaterials​ and their applications of sensors.
Ramkumar Reply
what is nano technology
Sravani Reply
what is system testing?
preparation of nanomaterial
Victor Reply
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
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Source:  OpenStax, Mathematics grade 3. OpenStax CNX. Oct 14, 2009 Download for free at http://cnx.org/content/col11128/1.1
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