Page 20 - SM Class 4 Inner.cdr

Example 9 : Add 214061, 142131 and 234250.
Solution : First method Second method

L TTh Th H T O L TTh Th H T O
1
1
2 1 4 0 6 1 1 4 2 1 3 1
+ 1 4 2 1 3 1 + 2 3 4 2 5 0
3 5 6 1 9 2 3 7 6 3 8 1

L TTh Th H T O L TTh Th H T O
1
1
3 5 6 1 9 2 3 7 6 3 8 1
+ 2 3 4 2 5 0 + 2 1 4 0 6 1
5 9 0 4 4 2 5 9 0 4 4 2

We see that (214061 + 142131) + 234250 = (142131 + 234250) + 214061.
The answer remains the same.

E xercise 2.1

1. Find the sum of the following addends :

a. 43231 + 50712 b. 18541 + 75338
c. 60511 +32024 d. 52693 +43316

e. 14205 +44524 + 23752 f. 50891 + 23454 + 15679
g. 13022 + 32143 +27587 h. 23921 +42146 +27438

i. 14567 +23098 + 12873 j. 43907 + 21609 +95426
k. 92838 + 28352 +23875 l. 52809 + 24152 + 10474

2. Arrange in columns and find the sum :
a. 235786 +421012 +164320 b. 109832 + 590146 + 243281

c. 342019 + 452807 +221573 d. 572480 +125319 + 204590
e. 243157 +256311 + 540650 f. 246789 + 279874 + 200092

g. 125793 +120530 +420295 h. 175234 +375206 +753842

3. Fill in the blanks :

a. 234563 + 123725 = 123725 + _______ = _______

b. 354789 + _______ = 0 + 354789 = _______

c. 121215 + 346780 + 123442 = 123442 + _______ + 346780 = _______

d. 0 + _______ = 347890 + 0 = _______

e. 113307 +143526 +722431 = 722431 + _______ + 143526 = _______

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Mathematics In Focus - 4