Method 1:
Example :
Answer:
458 + 243
= 458 + 200 + 40 + 3 = 658 + 40 + 3 = 698 + 3 = 701
Method 2:
Example :
Method 3:
Example :
Answer:
a) 123 → 120
244 → 240
120 + 240 = 360
Add the deficiency.
3 + 4 = 7
360 + 7 = 367
b) 286 → 290
479 → 480
290 + 480 = 770
Then subtract the deficiency.
4 + 1 = 5
770 – 5 = 765
Method 4:
Example :
Answer:
a) 141 + 426 =
Turn 141 to 140 and 426 to 427 by subtracting and adding 1 respectively.
Now, 140 + 427 = 567
Hence, 141 + 426 = 567
b) 589 + 356 =
Turn 589 to 590 and 356 to 355 by adding and subtracting 1 respectively.
Now, 590 + 355 = 945
Hence, 589 + 356 = 945.
Method 5:
Example :
Answer:
a) 518 + 5 = 518 + 2 + 3
= 520 + 3 = 523
b) 729 + 6 = 729 + 1 + 5
= 730 + 5 = 735
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