Number Addition and Subtraction
NZC LEVEL 2
Number Strategies NAS2-1 Use simple additive strategies with whole numbers and fractions. Number Knowledge NAK2-1 Know forward and backward counting sequences with whole numbers to at least 1000. NAK2-2 Know the basic addition and subtraction facts. NAK2-3 Know hoe many ones, tens, and hundreds are in whole numbers to at least 1000. NAK2-4 Know simple fractions in everyday use. |
NZC LEVEL 3
Number Strategies NAS3-1 Use a range of additive and simple multiplicative strategies with whole numbers, fractions, decimals, and percentages. Number Knowledge NAK3-1 Know basic multiplication and division facts NAK3-2 Know counting sequences for whole numbers. NAK3-3 Know how many tenths, tens, hundreds, and thousands are in whole numbers. NAK3-4 Know fractions and percentages in everyday use. |
NZC LEVEL 4
Number Strategies and Knowledge NA4-1 Use a range of multiplicative strategies when operating whole numbers. NA4-2 Understand addition and subtraction of fractions, decimals and integers. NA4-3 Find fractions, decimals and percentages of amounts expressed as whole numbers, simple fractions and decimals. NA4-4 Apply simple linear proportions, including ordering fractions. NA4-5 Know the equivalent decimal and percentage forms for everyday fractions. NA4-6 Now the relative size and place value structure of positive and negative integers and decimals to three decimal places. |
NZC LEVEL 5
Number Strategies and Knowledge NA5-1 Reason with linear proportions. NA5-2 Use prime numbers, common factors and multiples and powers (including square roots). NA5-3 Understand operations on fractions, decimals, percentages, and integers. NA5-4 Use rates and ratios. NA5-5 Know commonly used fraction, decimal, and percentage conversions. NA5-6 Know and apply standard form, significant figures, rounding, and decimal place value. |
In this unit you will learn:
1) Rounding 2) Adding and subtracting by making Tidy Numbers 3) Adding and Subtracting using Near Doubles 4) Adding and subtracting by Equal Addition 5) Adding and Subtracting by Partitioning 6) Adding and Subtracting by using a Number Line |
7) Adding and Subtracting using Written Algorithms
8) Adding Decimals 9) Subtracting Decimals 10) Introducing Integers 11) Adding and Subtracting Integers |
1) Rounding
- We round numbers when an exact answer is not needed.
- Tidy numbers end in zero.
- Numbers can be written to the nearest ten, hundred or thousand so that calculations can be done mentally.
- Numbers that are halfway between two other numbers are usually rounded up, e.g. 15 is rounded up to 20.
Click on this link to take you to a Rounding Game
https://www.mathsisfun.com/rounding-numbers.html
2) Adding and Subtracting by making TIDY NUMBERS
We have looked at the tidy number strategy to help us with addition and subtraction problems. We learnt that by making one of the numbers in our problem a tidy number (i.e. a number that ends in a zero) we are able to solve the problem much easier. Addition Tidy Number Strategy For example if our addition problem was: 48 + 7 = STEP 1: Making a Tidy Number If we first round the 48 up to 50 by taking 2 off the 7 we are then left with the easier problem of: 50 + 5 = The 5 is what is left after taking the 2 off the 7. We then know our answer is 55 so we solve our problem: 48 + 7 = 55 Subtraction Tidy Number Strategy For example if our subtraction problem was: 48 - 7 = STEP 1: Making a Tidy Number If we first round the 48 up to 50 by adding 2 to the 48 we need to make sure we add two to the 7 as well so that the gap between the two numbers remains the same (i.e. there is always a gap of 41 between the numbers in our example). We are then left with the easier problem of: 50 - 9 = STEP 2: Using our basic facts to help us solve the problem We could then approach this problem by using our basic fact of 10 - 9 = 1 Instead of 10 we however have 50 so our answer is going to be in the 40s. 50 - 9 = 41 |
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3) Adding and Subtracting using NEAR DOUBLES
Try these: a. 37 + 39 = b. 41 + 37 = c. 36 + 35 = d. 56 + 48 = e. 123 + 125 = f. 63 - 31 = g. 152 - 75 = h. 91 - 45 = |
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4) Adding and Subtracting by EQUAL ADDITION
- Numbers can be added by making one number a tidy number and then subtracting the same amount from the other number.
- Numbers can be subtracted by making one number a tidy number and then adding the same amount to the other number - this is called equal addition.
5) Adding and Subtracting by Partitioning
6) Adding and Subtracting using a NUMBER LINE
- Empty number lines are a useful tool for adding and subtracting numbers. On an empty number line the scale isn't important.
- Numbers can be added or subtracted on a number line by JUMPING THROUGH A TIDY NUMBER.
Check out these links to have a go....
- https://www.khanacademy.org/math/early-math/cc-early-math-add-sub-100/cc-early-math-add-sub-100-word-problems/e/adding-and-subtracting-on-the-number-line-word-problems
- http://www.mathsisfun.com/numbers/number-line-using.html
- http://www.math-aids.com/Number_Lines/
- http://www.mathworksheets4kids.com/number-lines.html
- https://www.tes.co.uk/teaching-resource/number-line-strategies--addition-and-subtraction-63027
7) Adding and Subtracting using WRITTEN ALGORITHMS
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8) Adding Decimals
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9) Subtracting Decimals
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Look at this fabulous clip on Adding and Subtracting Decimals...
Check out these website on adding and subtracting decimals
https://www.mathsisfun.com/adding-decimals.html
http://www.mathgoodies.com/lessons/decimals/solve_word_problems.html
https://www.mathsisfun.com/adding-decimals.html
http://www.mathgoodies.com/lessons/decimals/solve_word_problems.html
10) Introducing Integers
- Integers are the numbers..., -5, -4, -3, -2, -1, 0, 1, 2, 3, 4, 5, .....
- The ... means that the numbers go on forever in both directions.
- Integers can be shown on horizontal or vertical number lines. These are not empty number lines, they are drawn to scale.
- -2 is read as negative 2. +2 is read as positive 2. Numbers without signs are positive.
- Positive numbers are to the right of the zero; negative numbers are to the left of the zero.
- Larger numbers are to the right on a horizontal number line, or to the top on a vertical number line.
https://www.slideshare.net/TaraCampbell0510/integers-8505366
11) Adding and Subtracting Integers
Check out these sites to have a go at adding and subtracting integers...
http://www.mathsisfun.com/positive-negative-integers.html
http://www.math-play.com/integers-game.html
http://www.math.com/school/subject1/lessons/S1U1L11GL.html
If you need some more help have a look at the You Tube clip below.
http://www.mathsisfun.com/positive-negative-integers.html
http://www.math-play.com/integers-game.html
http://www.math.com/school/subject1/lessons/S1U1L11GL.html
If you need some more help have a look at the You Tube clip below.
Integer Games...have fun!
Addition and Subtraction Word Problems
Decimal Addition Word Problems |
Decimal Subtraction Word Problems |