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Adding 100

When we add '100' to a number, the value of the digit at the hundreds place increases by
1 and tens and the ones digits remain the same.
Examples: (a) 643 + 100 = 743 (b) 1785 + 100 = 1885

Adding 1000

When we add '1000' to a number, the value of the digit at the thousands place increases

by 1 and the hundreds, tens and ones digits remain the same.
Examples: (a) 6523 + 1000 = 7523 (b) 7092 + 1000 = 8092

Adding 9, 99, and 999

When you add 9, 99, or 999 to a number, think of it as adding 10, 100, or 1000 respectively
and then subtracting 1. This helps make the addition easier.

Example: (a) 45 + 9 = 45 + 10 – 1 = 55 – 1 = 54 (b) 76 + 99 = 76 + 100 – 1 = 176 – 1 = 175
(c) 894 + 999 = 894 + 1000 – 1 = 1894 – 1 = 1893

practice time 2F

1. Fill in the blanks using the properties of addition.

(a) 124 + 0 = ______ (b) _____ + 0 = 675 (c) 8926 + ____ = 8926

(d) 4678 + 1 = ______ (e) 3564 + _____ = 3565 (f) _______ + 1 = 4576
2. Find the missing numbers.

(a) 74 + ____ = 84 (b) ____ + 55 = 65 (c) 4362 + ____ = 4462

(d) ____ + 5346 = 5446 (e) 3040 + 99 = ____ (f) 9 + 1736 = ____

3. Find the sum of the following using the properties of addition.

(a) 542 + 10 (b) 789 + 100 (c) 10 + 7235
(d) 4178 + 100 (e) 6965 + 100 (f) 6743 + 100
(g) 100 + 3144 (h) 612 + 1000 (i) 6283 + 1000

4. Add the following numbers. Then, change the order of the addends to verify the

order property of the addition.
(a) 635 + 298 (b) 563 + 375

H t O H t O H t O H t O

+ + + +

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