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Example 3: Add 243, 312 and 143.

Solution: Step 1 Step 2 Step 3
H T O H T O H T O

2 4 3 2 4 3 2 4 3
3 1 2 3 1 2 3 1 2

+ 1 4 3 + 1 4 3 + 1 4 3

8 9 8 6 9 8

So, 243 + 312 + 143 = 698.

Exercise 2.1

1. Add the given numbers.

(a) H T O (b) H T O (c) H T O

3 3 2 9 2 7 3 5 8

+ 5 4 + 5 2 + 3 1

(d) H T O (e) H T O (f) H T O

6 1 3 4 9 2 1 1 2
+ 2 8 6 + 3 0 6 + 3 1 5

(g) H T O (h) H T O (i) H T O

4 2 7 4 1 1 2 0 0
3 4 0 1 5 1 6 5 1

+ 2 3 0 + 2 3 7 + 3 8

2. Find the sum.

(a) 823 + 46 (b) 215 + 42 (c) 231 + 333 (d) 100 + 680 + 117

Mental Maths

Solve the given problems.
(a) 427 increased by 12 is _______. (b) 635 added to 4 is _______.
(c) 21 + 178 gives _______. (d) 15 added to 453 is _______.

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