Unit 15 – The four operations
1 We can use what we know about counting by 100 to help add and subtract. 354 + 200 354 − 200
− 100 − 100
+ 100 + 100
154
254 354
354
454 554
This is the same as counting back two jumps of 100.
This is the same as counting on two jumps of 100.
The hundreds digits change and the tens and ones digits stay the same.
Copy and complete these counts. (a) Count on by 100 from 382.
1
(b) Count back by 100 from 875.
2 Copy and complete. What patterns do you notice?
382 + 100 = 382 + 200 = 382 + 300 = 382 +
875 − 100 = 875 − 200 = 875 − 300 = 875 −
382 + 600 = 982 − 600 = 875 − 500 = 375 +
= 875
= 782
= 475
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03/05/2022 10:20
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