+
0
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7
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9
10
0
0
1
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10
1
1
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5
6
7
8
9
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11
2
2
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4
5
6
7
8
9
10
11
12
3
3
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5
6
7
8
9
10
11
12
13
4
4
5
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7
8
9
10
11
12
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14
5
5
6
7
8
9
10
11
12
13
14
15
6
6
7
8
9
10
11
12
13
14
15
16
7
7
8
9
10
11
12
13
14
15
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17
8
8
9
10
11
12
13
14
15
16
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18
9
9
10
11
12
13
14
15
16
17
18
19
10
10
11
12
13
14
15
16
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20

Why does 0 + 1 = 1?

Let's start at 0.

Next, let's count 1 times.

Ready? ... 0, 11.

That's why 0 + 1 = 1.

Mathgrow

0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9