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2.14.

Double-parentheses tasks within the 0–20 number range

LEVEL 3

1.
2.

LEVEL 5

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4.
5.
6.

LEVEL 6

7.
8.

LEVEL 7

9.
10.
11.
12.
13.
14.

LEVEL 8

15.
16.
17.

LEVEL 9

18.
19.
20.
21.
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