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More addition and subtraction to 800
Term 3
Number families
We can make families of numbers.
Each family has two bigger numbers and one smaller number.
Take 4, 8 and 12 as an example.
Find the families.
Write 4 number sentences for each group of numbers.
| 6 8 14 | ||||
| 17 17 34 | ||||
| 25 45 70 | ||||
| 65 335 400 | ||||
| 240 260 500 |
Look for links.
In this activity we are going to identify the pattern.
|
360 – 50 = |
50 + = 360 |
+ 50 = 360 |
|
570 – 480 = |
480 + = 570 |
+ 480 = 570 |
|
430 – 31 = |
31 + = 430 |
+ 31 = 430 |
|
676 – 70 = |
70 + = 676 |
+ 70 = 676 |
|
799 – 701 = |
701 + = 799 |
+ 701 = 799 |
A long drive.
Mr Mkhize drives to visit his mother who lives 352 km away. He makes a stop after 166 km. How much further must he travel?
| Kumi does this: | Phumla wrote this: |
|
352 – 166 +4 + 30 + 100 + 52
166 170 200 300 352 166 170 200 300 352 = 134 + 52 = 186 km |
352 – 166 = 300 + 50 + 2 – 100 + 60 + 6 = 300 + 40 + 12 – 100 + 60 + 6 = 200 + 140 + 12 – 100 + 60 + 6 = 100 + 80 + 6 = 186 km |
| Mbali does this: | Peter does this: |
|
352 – 166 166 + 100 ➞ 266 + 34 ➞ 300 + 52 ➞ 352 100 + 34 + 52 = 134 + 52 = 186 km |
352 – 166 = 352 – 100 – 66 = 252 – 66 = 252 – 52 – 14 = 200 – 14 = 186 km |
| Veronica does this: | Lebo thinks doubles and halves: |
|
352 – 166 352 – 152 = 200 200 – 14 = 200 – 10 – 4 = 190 – 4 = 186 km |
Half of 352 is 176 |
Solve the following on an extra piece of paper:
Use any of the above methods.
|
746 – 328 |
|
800 – 499 |
